diff --git a/waiting_room/WaitingRoom/Node.cs b/waiting_room/WaitingRoom/Node.cs
index 7bcec34..b1f3c09 100644
--- a/waiting_room/WaitingRoom/Node.cs
+++ b/waiting_room/WaitingRoom/Node.cs
@@ -6,5 +6,11 @@
 /// </summary>
 public sealed class Node
 {
-    // TODO 
+    public Patient Data { get; }
+    public Node? Next { get; set; }
+
+    public Node(Patient patient)
+    {
+        Data = patient;
+    }
 }
\ No newline at end of file
diff --git a/waiting_room/WaitingRoom/Patient.cs b/waiting_room/WaitingRoom/Patient.cs
index 0b2b66f..83b9831 100644
--- a/waiting_room/WaitingRoom/Patient.cs
+++ b/waiting_room/WaitingRoom/Patient.cs
@@ -5,7 +5,18 @@
 /// </summary>
 public sealed class Patient
 {
-    // TODO ctor
+    public Patient(string name, DateTime arrival)
+    {
+        Name = name;
+        Arrival = arrival;
+    }
+    
+    public Patient(string name, DateTime arrival, bool isEmergency)
+    {
+        Name = name;
+        Arrival = arrival;
+        IsEmergency = isEmergency;
+    }
 
     /// <summary>
     ///     Gets the name of the patient
diff --git a/waiting_room/WaitingRoom/PatientQueue.cs b/waiting_room/WaitingRoom/PatientQueue.cs
index 32f43d4..ba4c372 100644
--- a/waiting_room/WaitingRoom/PatientQueue.cs
+++ b/waiting_room/WaitingRoom/PatientQueue.cs
@@ -6,7 +6,7 @@
 /// </summary>
 public sealed class PatientQueue
 {
-    //private Node? _head;
+    private Node? _head;
 
     /// <summary>
     ///     Gets the number of patients currently waiting in this queue
@@ -20,7 +20,25 @@ public sealed class PatientQueue
     /// <param name="patient">Patient to add to the queue</param>
     public void Enqueue(Patient patient)
     {
-        // TODO
+        var newNode = new Node(patient);
+        
+        if (_head == null || patient.Arrival < _head.Data.Arrival)
+        {
+            newNode.Next = _head;
+            _head = newNode;
+            Size++;
+            return;
+        }
+
+        var current = _head;
+        while (current.Next != null && current.Next.Data.Arrival <= patient.Arrival)
+        {
+            current = current.Next;
+        }
+        
+        newNode.Next = current.Next;
+        current.Next = newNode;
+        Size++;
     }
 
     /// <summary>
@@ -29,8 +47,15 @@ public sealed class PatientQueue
     /// <returns>The next patient to be treated; null if no patient is waiting</returns>
     public Patient? Dequeue()
     {
-        // TODO
-        return null;
+        if (_head == null)
+        {
+            return null;
+        }
+
+        var patient = _head.Data;
+        _head = _head.Next;
+        Size--;
+        return patient;
     }
 
     /// <summary>
@@ -41,7 +66,31 @@ public sealed class PatientQueue
     /// <returns>True if the patient could be removed; false otherwise</returns>
     public bool Remove(Patient patient)
     {
-        // TODO
-        return false;
+        if (_head == null)
+        {
+            return false;
+        }
+
+        if (_head.Data == patient)
+        {
+            _head = _head.Next;
+            Size--;
+            return true;
+        }
+
+        var current = _head;
+        while (current.Next != null && current.Next.Data != patient)
+        {
+            current = current.Next;
+        }
+
+        if (current.Next == null)
+        {
+            return false;
+        }
+
+        current.Next = current.Next.Next;
+        Size--;
+        return true;
     }
 }
\ No newline at end of file
diff --git a/waiting_room/WaitingRoom/WaitingRoom.cs b/waiting_room/WaitingRoom/WaitingRoom.cs
index 077982d..a49be65 100644
--- a/waiting_room/WaitingRoom/WaitingRoom.cs
+++ b/waiting_room/WaitingRoom/WaitingRoom.cs
@@ -14,20 +14,17 @@ public sealed class WaitingRoom
     /// <summary>
     ///     Gets the current number of emergency patients waiting
     /// </summary>
-    // TODO
-    public int CountEmergency => -1;
+    public int CountEmergency => _emergencyQueue.Size;
     
     /// <summary>
     ///     Gets the current number of normal patients waiting
     /// </summary>
-    // TODO
-    public int CountNormal => -1;
+    public int CountNormal => _normalQueue.Size;
     
     /// <summary>
     ///     Gets the current number of all patients waiting
     /// </summary>
-    // TODO
-    public int CountAll => -1;
+    public int CountAll => CountEmergency + CountNormal;
 
     /// <summary>
     ///     Creates a string representation of the waiting room, showing statistics
@@ -43,15 +40,25 @@ public sealed class WaitingRoom
     /// <param name="patient">Patient to admit</param>
     public void AddPatient(Patient patient)
     {
-        // TODO
+        if (patient.IsEmergency)
+        {
+            _emergencyQueue.Enqueue(patient);
+        }
+        else
+        {
+            _normalQueue.Enqueue(patient);
+        }
     }
 
     /// <summary>
     ///     Returns the next patient to be treated, removing it from its waiting queue
     /// </summary>
     /// <returns>Next patient to treat, if any</returns>
-    // TODO
-    public Patient? Next() => null;
+    public Patient? Next()
+    {
+        var emergency = _emergencyQueue.Dequeue();
+        return emergency ?? _normalQueue.Dequeue();
+    }
 
     /// <summary>
     ///     Promotes a patient to be an emergency case.
@@ -60,6 +67,12 @@ public sealed class WaitingRoom
     /// <param name="patient">Patient to declare an emergency for</param>
     public void SetPatientToEmergency(Patient patient)
     {
-        // TODO
+        if (!_normalQueue.Remove(patient))
+        {
+            return;
+        }
+
+        patient.IsEmergency = true;
+        _emergencyQueue.Enqueue(patient);
     }
 }
\ No newline at end of file