diff --git a/api/src/main/java/org/openmrs/api/MedicationDispenseService.java b/api/src/main/java/org/openmrs/api/MedicationDispenseService.java
index dfdf54c3f0dc..14fb32743fea 100644
--- a/api/src/main/java/org/openmrs/api/MedicationDispenseService.java
+++ b/api/src/main/java/org/openmrs/api/MedicationDispenseService.java
@@ -26,6 +26,7 @@ public interface MedicationDispenseService extends OpenmrsService {
 	 * Gets a MedicationDispense by id
 	 * @param medicationDispenseId the id of the MedicationDispense to retrieve
 	 * @return the MedicationDispense with the given id, or null if none exists
+	 * @throws IllegalArgumentException if medicationDispenseId is null
 	 */
 	@Authorized({ PrivilegeConstants.GET_MEDICATION_DISPENSE })
 	MedicationDispense getMedicationDispense(Integer medicationDispenseId);
@@ -34,15 +35,16 @@ public interface MedicationDispenseService extends OpenmrsService {
 	 * Gets a MedicationDispense based on the uuid
 	 *
 	 * @param uuid - uuid of the MedicationDispense to be returned
-	 * @return the MedicationDispense
+	 * @return the MedicationDispense, or null if not found
+	 * @throws IllegalArgumentException if uuid is null or empty
 	 */
 	@Authorized({ PrivilegeConstants.GET_MEDICATION_DISPENSE })
 	MedicationDispense getMedicationDispenseByUuid(String uuid);
 
-    /**
+	/**
 	 * Gets all MedicationDispense results that match the given criteria
 	 * @param criteria - the criteria for the returned MedicationDispense results
-	 * @return a list of MedicationDispenses
+	 * @return a list of MedicationDispenses, or an empty list if no matches are found
 	 */
 	@Authorized({ PrivilegeConstants.GET_MEDICATION_DISPENSE })
 	List<MedicationDispense> getMedicationDispenseByCriteria(MedicationDispenseCriteria criteria);
@@ -50,6 +52,8 @@ public interface MedicationDispenseService extends OpenmrsService {
 	/**
 	 * Saves a MedicationDispense
 	 * @param medicationDispense - the MedicationDispense to be saved
+	 * @return the saved MedicationDispense instance
+	 * @throws IllegalArgumentException if medicationDispense is null
 	 */
 	@Authorized({ PrivilegeConstants.EDIT_MEDICATION_DISPENSE })
 	MedicationDispense saveMedicationDispense(MedicationDispense medicationDispense);
@@ -58,6 +62,8 @@ public interface MedicationDispenseService extends OpenmrsService {
 	 * Voids a MedicationDispense
 	 * @param medicationDispense the MedicationDispense to be voided
 	 * @param reason the reason for voiding the MedicationDispense
+	 * @return the voided MedicationDispense
+	 * @throws IllegalArgumentException if medicationDispense or reason is null
 	 */
 	@Authorized({ PrivilegeConstants.EDIT_MEDICATION_DISPENSE })
 	MedicationDispense voidMedicationDispense(MedicationDispense medicationDispense, String reason);
@@ -65,6 +71,8 @@ public interface MedicationDispenseService extends OpenmrsService {
 	/**
 	 * Un-void a previously voided MedicationDispense
 	 * @param medicationDispense MedicationDispense to un-void
+	 * @return the un-voided MedicationDispense
+	 * @throws IllegalArgumentException if medicationDispense is null
 	 */
 	@Authorized(PrivilegeConstants.EDIT_MEDICATION_DISPENSE)
 	MedicationDispense unvoidMedicationDispense(MedicationDispense medicationDispense);
@@ -72,9 +80,12 @@ public interface MedicationDispenseService extends OpenmrsService {
 	/**
 	 * Completely remove a MedicationDispense from the database. This should typically not be called
 	 * because we don't want to ever lose data. The data really <i>should</i> be voided and then it
-	 * is not seen in interface any longer (see #voidMedicationDispense(MedicationDispense) for that one) 
+	 * is not seen in interface any longer (see #voidMedicationDispense(MedicationDispense) for that one)
 	 * If other data references this medicationDispense, an error will be thrown.
+	 *
 	 * @param medicationDispense the MedicationDispense to be purged
+	 * @throws IllegalArgumentException if medicationDispense is null
+	 * @throws UnsupportedOperationException if purging is restricted by business rules
 	 */
 	@Authorized(PrivilegeConstants.DELETE_MEDICATION_DISPENSE)
 	void purgeMedicationDispense(MedicationDispense medicationDispense);