The role of catecholamines in the mechanism of antiovulatory and other central effects of medroxyprogesterone acetate (MPA) has been studied in adult healthy, non-pregnant female albino rats. It has been observed that a single dose of MPA (100 mg/kg) given intramuscularly did not cause any significant change in brain catecholamine levels after 7 days of treatment. However, there was a significant reduction in brain dopamine levels after 15 days of MPA administration. This reduction in brain dopamine levels may be responsible for the anti-ovulatory activity of MPA. Certain side effects of MPA such as amenorrhoea, galactorrhoea, breast tenderness, breast tumors, inactivity and depression may also be due to decrease in brain dopamine levels.