The aim of this study was to compare the efficiency of dopamine agonist, Cabergoline, in decreasing the size of endometrioma, with that of luteinizing hormone releasing hormone (LHRH) agonist, triptorelin acetate. This was a prospective, randomized study. The setting was in two private medical centers in the UAE, from January 2011 to February 2012. One hundred and forty patients complaining of endometrioma, and fulfilling the eligibility criteria, were chosen and divided into two groups as follows: Group I comprised 71 patients; all of them received Cabergoline tablets, 0.5mg tablets, twice per week for 12weeks. Group II comprised 69 patients; all of them received LHRH agonist, decapeptyl, 3.75mg subcutaneous, single injection, once a month for 3months. All patients underwent vaginal ultrasound before and after the treatment period to compare the change in the size of endometrioma by the same sonography team in each hospital that was blind to the treatment groups. The outcome was measured by the changes in the endometrioma size by vaginal ultrasound after completion of the 3months' treatment period. The management line was considered to be significantly effective if the endometrioma size was reduced by more than 25% of its original pretreatment size. Group I: 46 out of the 71 patients (64.7%) had significant decrease in endometrioma size. Group II: 15 out of 69 patients (21.7%) had significant decrease in endometrioma size. Paired t test to compare the means of the two groups was highly significant (p<0.05) CONCLUSION: Cabergoline (dostinex) yields better results in decreasing the size of endometrioma, compared to LHRH-agonist by exerting antiangiogenic effects through vascular endothelial growth factor receptor-2 (VEGFR-2) inactivation. It has no major side effects, easier to administer, and cheaper than LHRH agonists.