Abstract: The use of a suitable regimen of cabergoline in prevention of OHSS with at least side effects is desirable. So this study aimed to evaluate daily versus once every two days administration of cabergoline to prevent and decrease the intensity of OHSS. Patients at risk of OHSS were chosen randomly and put alternately into two groups: Daily-treated (group I), in which the patients received oral cabergoline at the dose of 0.5 mg day-1 for 8 days (total of 8 tablets), Once every two days-treated (group II), in which the patients received a single 0.5 mg oral tablet of cabergoline once every two days for 8 days (total of 4 tablets). The day before human chorionic gonadotrophin (hCG) administration and on day 9, the two groups were assessed and compared for complaints, clinical, laboratory findings and also sonographic criteria of OHSS. The results were shown that effectiveness of daily administration of cabergoline is more than it’s once every two days administration on abdominal circumference increase, HCT, WBC, platelet count, abdominal pain, shortness of breath, ascites and increase in both ovaries size. However, the effectiveness of both treatment methods was same on increase in weight, oliguria and serum creatinine rise. On the other hand, daily administration of cabergoline was not meaningfully more effective than it’s once every two days administration in decreasing the incidence of all varieties of OHSS, but was effective in decreasing its intensity. The incidence of severe and moderate OHSS was less and cases with mild OHSS or no OHSS at all were more in the group using daily cabergoline. It seems that daily administration of cabergoline doesn’t has a greater effect than it’s once every two days administration, on decreasing the incidence of OHSS; but is more effective in decreasing the intensity of clinical features, laboratory and sonographic findings of OHSS.