diff --git a/src/lab15_observer/ex1/Main.java b/src/lab15_observer/ex1/Main.java
new file mode 100644
index 0000000..26edf66
--- /dev/null
+++ b/src/lab15_observer/ex1/Main.java
@@ -0,0 +1,24 @@
+package lab15_observer.ex1;
+
+public class Main {
+    public static void main(String[] args) {
+        PatientMonitoring pm = new PatientMonitoring(1, 140, 85);
+
+        MedicalEmployee jean = new MedicalEmployee("Jean", pm);
+        MedicalEmployee pauline = new MedicalEmployee("Pauline", pm);
+        MedicalEmployee matthieu = new MedicalEmployee("Matthieu", pm);
+        MedicalEmployee symeon = new MedicalEmployee("Symeon", pm);
+
+        pm.setBloodPressure(110);
+        pm.setPosition(3);
+
+        pm.setPulseOximetry(90);
+        pm.setPulseOximetry(70);
+        pm.setPosition(7);
+        pm.setBloodPressure(150);
+
+        pm.removeObserver(matthieu);
+        pm.setBloodPressure(145);
+        pm.setPosition(9);
+    }
+}
diff --git a/src/lab15_observer/ex1/MedicalEmployee.java b/src/lab15_observer/ex1/MedicalEmployee.java
new file mode 100644
index 0000000..f68fef5
--- /dev/null
+++ b/src/lab15_observer/ex1/MedicalEmployee.java
@@ -0,0 +1,19 @@
+package lab15_observer.ex1;
+
+public class MedicalEmployee implements PatientObserver {
+    private final String name;
+
+    public MedicalEmployee(String name, PatientMonitoring pm) {
+        this.name = name;
+        pm.registerObserver(this);
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public void update(Problem problem, PatientMonitoring pm) {
+        System.out.println(getName() + " has been notified of " + problem + " for patient " + pm);
+    }
+}
diff --git a/src/lab15_observer/ex1/PatientMonitoring.java b/src/lab15_observer/ex1/PatientMonitoring.java
new file mode 100644
index 0000000..190eb48
--- /dev/null
+++ b/src/lab15_observer/ex1/PatientMonitoring.java
@@ -0,0 +1,70 @@
+package lab15_observer.ex1;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class PatientMonitoring {
+    private final List<PatientObserver> observers = new ArrayList<>();
+
+    private int position;
+    private int bloodPressure;
+    private int pulseOximetry;
+
+    public PatientMonitoring(int position, int bloodPressure, int pulseOximetry) {
+        this.position = position;
+        this.bloodPressure = bloodPressure;
+        this.pulseOximetry = pulseOximetry;
+    }
+
+    public void registerObserver(PatientObserver o) {
+        observers.add(o);
+    }
+
+    public void removeObserver(PatientObserver o) {
+        observers.remove(o);
+    }
+
+    private void notifyObservers(Problem problem) {
+        for (PatientObserver o : observers) {
+            o.update(problem, this);
+        }
+    }
+
+    public int getPosition() {
+        return position;
+    }
+    public int getBloodPressure() {
+        return bloodPressure;
+    }
+    public int getPulseOximetry() {
+        return pulseOximetry;
+    }
+
+    public void setPosition(int position) {
+        this.position = position;
+        notifyObservers(Problem.NO_PROBLEM);
+    }
+
+    public void setBloodPressure(int bloodPressure) {
+        this.bloodPressure = bloodPressure;
+        if (getBloodPressure() > 145) {
+            notifyObservers(Problem.BLOOD_PRESSURE);
+        } else {
+            notifyObservers(Problem.NO_PROBLEM);
+        }
+    }
+
+    public void setPulseOximetry(int pulseOximetry) {
+        this.pulseOximetry = pulseOximetry;
+        if (getPulseOximetry() > 85) {
+            notifyObservers(Problem.OXIMETRY);
+        } else {
+            notifyObservers(Problem.NO_PROBLEM);
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "<Patient Position: " + position + ", BP: " + bloodPressure + ", PO: " + pulseOximetry + ">";
+    }
+}
diff --git a/src/lab15_observer/ex1/PatientObserver.java b/src/lab15_observer/ex1/PatientObserver.java
new file mode 100644
index 0000000..d025d85
--- /dev/null
+++ b/src/lab15_observer/ex1/PatientObserver.java
@@ -0,0 +1,5 @@
+package lab15_observer.ex1;
+
+public interface PatientObserver {
+    void update(Problem problem, PatientMonitoring pm);
+}
diff --git a/src/lab15_observer/ex1/Problem.java b/src/lab15_observer/ex1/Problem.java
new file mode 100644
index 0000000..ad3708d
--- /dev/null
+++ b/src/lab15_observer/ex1/Problem.java
@@ -0,0 +1,7 @@
+package lab15_observer.ex1;
+
+public enum Problem {
+    NO_PROBLEM,
+    BLOOD_PRESSURE,
+    OXIMETRY
+}