diff --git a/src/main/scala/Sort/FunctionalMergeSort.scala b/src/main/scala/Sort/FunctionalMergeSort.scala
new file mode 100644
index 0000000..1c8f285
--- /dev/null
+++ b/src/main/scala/Sort/FunctionalMergeSort.scala
@@ -0,0 +1,30 @@
+package Sort
+
+object FunctionalMergeSort {
+
+  /** @param vector
+    *   - a vector of unsorted integers
+    * @return
+    *   - vector of sorted integers @vector
+    */
+
+  @scala.annotation.tailrec
+  def merge(lh: Vector[Int], uh: Vector[Int], acc: Vector[Int] = Vector()): Vector[Int] = {
+    (lh, uh) match {
+      case (lhd +: ltl, uhd +: _) if lhd <= uhd => merge(ltl.toVector, uh, acc.appended(lhd))
+      case (lhd +: _, uhd +: utl) if lhd > uhd  => merge(lh, utl.toVector, acc.appended(uhd))
+      case (Vector(), uh)                       => acc ++ uh
+      case _                                    => acc ++ lh
+    }
+  }
+
+  def mergeSort(xs: Vector[Int]): Vector[Int] = {
+    if (xs.length <= 1) xs
+    else {
+      val m        = xs.length / 2
+      val (lh, uh) = xs.splitAt(m)
+      merge(mergeSort(lh), mergeSort(uh))
+    }
+  }
+
+}
diff --git a/src/test/scala/Sort/FunctionalMergeSortSpec.scala b/src/test/scala/Sort/FunctionalMergeSortSpec.scala
new file mode 100644
index 0000000..3050880
--- /dev/null
+++ b/src/test/scala/Sort/FunctionalMergeSortSpec.scala
@@ -0,0 +1,12 @@
+package Sort
+
+import org.scalatest.flatspec.AnyFlatSpec
+
+class FunctionalMergeSortSpec extends AnyFlatSpec {
+
+  "A Merge Sort" should "return a sorted version of a vector passed to it" in {
+    val vec = Vector(3, 2, 7, 1, 9, 0)
+    assert(FunctionalMergeSort.mergeSort(vec) === Vector(0, 1, 2, 3, 7, 9))
+  }
+
+}