diff --git a/gen/midas.py b/gen/midas.py
index dc0efd0..e1c304d 100644
--- a/gen/midas.py
+++ b/gen/midas.py
@@ -111,10 +111,6 @@ class ConstraintType:
     constraint: Expr
 
 
-class UnionType:
-    types: list[Type]
-
-
 class ComplexType:
     properties: list[PropertyStmt]
 
diff --git a/midas/ast/midas.py b/midas/ast/midas.py
index a18b460..335e5cf 100644
--- a/midas/ast/midas.py
+++ b/midas/ast/midas.py
@@ -228,9 +228,6 @@ class Type(ABC):
         @abstractmethod
         def visit_constraint_type(self, type: ConstraintType) -> T: ...
 
-        @abstractmethod
-        def visit_union_type(self, type: UnionType) -> T: ...
-
         @abstractmethod
         def visit_complex_type(self, type: ComplexType) -> T: ...
 
@@ -261,14 +258,6 @@ class ConstraintType(Type):
         return visitor.visit_constraint_type(self)
 
 
-@dataclass(frozen=True)
-class UnionType(Type):
-    types: list[Type]
-
-    def accept(self, visitor: Type.Visitor[T]) -> T:
-        return visitor.visit_union_type(self)
-
-
 @dataclass(frozen=True)
 class ComplexType(Type):
     properties: list[PropertyStmt]
diff --git a/midas/ast/printer.py b/midas/ast/printer.py
index ee59279..41dd6a0 100644
--- a/midas/ast/printer.py
+++ b/midas/ast/printer.py
@@ -252,17 +252,6 @@ class MidasAstPrinter(
             with self._child_level(single=True):
                 type.constraint.accept(self)
 
-    def visit_union_type(self, type: m.UnionType) -> None:
-        self._write_line("UnionType")
-        with self._child_level():
-            self._write_line("types", last=True)
-            with self._child_level():
-                for i, type_ in enumerate(type.types):
-                    self._idx = i
-                    if i == len(type.types) - 1:
-                        self._mark_last()
-                    type_.accept(self)
-
     def visit_complex_type(self, type: m.ComplexType) -> None:
         self._write_line("ComplexType")
         with self._child_level():
@@ -379,10 +368,6 @@ class MidasPrinter(m.Expr.Visitor[str], m.Stmt.Visitor[str], m.Type.Visitor[str]
         res += " where " + type.constraint.accept(self)
         return res
 
-    def visit_union_type(self, type: m.UnionType) -> str:
-        types: list[str] = [type_.accept(self) for type_ in type.types]
-        return " | ".join(types)
-
     def visit_complex_type(self, type: m.ComplexType) -> str:
         res: str = "{\n"
         self.level += 1
diff --git a/midas/checker/types.py b/midas/checker/types.py
index d9d91b7..d62c867 100644
--- a/midas/checker/types.py
+++ b/midas/checker/types.py
@@ -44,11 +44,4 @@ class ComplexType:
     properties: dict[str, Type]
 
 
-@dataclass(frozen=True, kw_only=True)
-class UnionType:
-    alternatives: list[Type]
-
-
-Type = (
-    BaseType | AliasType | UnknownType | UnitType | Function | ComplexType | UnionType
-)
+Type = BaseType | AliasType | UnknownType | UnitType | Function | ComplexType
diff --git a/midas/cli/highlighter.py b/midas/cli/highlighter.py
index 690c408..b1b705f 100644
--- a/midas/cli/highlighter.py
+++ b/midas/cli/highlighter.py
@@ -294,11 +294,6 @@ class MidasHighlighter(
         type.type.accept(self)
         type.constraint.accept(self)
 
-    def visit_union_type(self, type: m.UnionType) -> None:
-        self.wrap(type, "union-type")
-        for type_ in type.types:
-            type_.accept(self)
-
     def visit_complex_type(self, type: m.ComplexType) -> None:
         self.wrap(type, "complex-type")
         for prop in type.properties:
diff --git a/midas/cli/hl_midas.css b/midas/cli/hl_midas.css
index f5b3d1d..fabb84e 100644
--- a/midas/cli/hl_midas.css
+++ b/midas/cli/hl_midas.css
@@ -8,7 +8,6 @@ span {
     &.named-type,
     &.generic-type,
     &.constraint-type,
-    &.union-type,
     &.complex-type {
         --col: 150, 150, 150;
     }
diff --git a/midas/lexer/midas.py b/midas/lexer/midas.py
index eec44d5..124ea09 100644
--- a/midas/lexer/midas.py
+++ b/midas/lexer/midas.py
@@ -18,8 +18,6 @@ class MidasLexer(Lexer):
                 self.add_token(TokenType.LEFT_BRACE)
             case "}":
                 self.add_token(TokenType.RIGHT_BRACE)
-            case "|":
-                self.add_token(TokenType.PIPE)
             case "<":
                 self.add_token(
                     TokenType.LESS_EQUAL if self.match("=") else TokenType.LESS
diff --git a/midas/lexer/token.py b/midas/lexer/token.py
index 9b30940..f08964a 100644
--- a/midas/lexer/token.py
+++ b/midas/lexer/token.py
@@ -23,7 +23,6 @@ class TokenType(Enum):
     AND = auto()
     QMARK = auto()
     DOT = auto()
-    PIPE = auto()
 
     # Operators
     # PLUS = auto()
diff --git a/midas/parser/midas.py b/midas/parser/midas.py
index 9af46da..5d09b83 100644
--- a/midas/parser/midas.py
+++ b/midas/parser/midas.py
@@ -20,7 +20,6 @@ from midas.ast.midas import (
     Type,
     TypeStmt,
     UnaryExpr,
-    UnionType,
     VariableExpr,
     WildcardExpr,
 )
@@ -161,18 +160,7 @@ class MidasParser(Parser):
         Returns:
             TypeExpr: the parsed type expression
         """
-        return self.union_type()
-
-    def union_type(self) -> Type:
-        types: list[Type] = [self.constraint_type()]
-        while self.match(TokenType.PIPE):
-            types.append(self.constraint_type())
-        if len(types) == 1:
-            return types[0]
-        return UnionType(
-            location=Location.span(types[0].location, types[-1].location),
-            types=types,
-        )
+        return self.constraint_type()
 
     def constraint_type(self) -> Type:
         type: Type = self.base_type()
diff --git a/midas/resolver/midas.py b/midas/resolver/midas.py
index 9ffce85..acbbe96 100644
--- a/midas/resolver/midas.py
+++ b/midas/resolver/midas.py
@@ -4,7 +4,6 @@ import midas.ast.midas as m
 from midas.checker.types import (
     AliasType,
     Type,
-    UnionType,
     UnknownType,
 )
 from midas.resolver.builtin import define_builtins
@@ -157,10 +156,6 @@ class MidasResolver(m.Stmt.Visitor[None], m.Expr.Visitor[None], m.Type.Visitor[T
         # TODO
         return UnknownType()
 
-    def visit_union_type(self, type: m.UnionType) -> Type:
-        types: list[Type] = [type_.accept(self) for type_ in type.types]
-        return UnionType(alternatives=types)
-
     def visit_complex_type(self, type: m.ComplexType) -> Type:
         for prop in type.properties:
             prop.accept(self)
diff --git a/tests/serializer/midas.py b/tests/serializer/midas.py
index 6da0dec..919dc66 100644
--- a/tests/serializer/midas.py
+++ b/tests/serializer/midas.py
@@ -19,7 +19,6 @@ from midas.ast.midas import (
     Type,
     TypeStmt,
     UnaryExpr,
-    UnionType,
     VariableExpr,
     WildcardExpr,
 )
@@ -161,12 +160,6 @@ class MidasAstJsonSerializer(
             "constraint": type.constraint.accept(self),
         }
 
-    def visit_union_type(self, type: UnionType) -> dict:
-        return {
-            "_type": "UnionType",
-            "types": self._serialize_list(type.types),
-        }
-
     def visit_complex_type(self, type: ComplexType) -> dict:
         return {
             "_type": "ComplexType",