Medroxyprogesterone acetate (MPA) is a steroidal progestin which is used as a contraceptive, in hormone replacement therapy, dysmenorrhea and amenorrhea. A 19-year-old female with bipolar affective disorder who was started on MPA for the treatment of secondary amenorrhea developed manic episodes while taking MPA pills. She was in remission for three years when MPA was commenced. As manic symptoms emerged following the onset of MPA treatment, risperidone and valproic acid was administered, which was then switched to aripiprazole and lithium treatment because of side effects. The manic episode resolved three weeks after hospital admission. This case report highlights the risk of commencing hormone pills in patients with personal history of affective disorders because of the possibility of MPA-induced manic episode.