This randomized, multicenter, parallel group study evaluated four new oral contraceptive regimens of norgestimate (NGM) and ethinyl estradiol (EE) relative to ORTHO TRI-CYCLEN (NGM 180/215/250 microg/EE 35 microg). Healthy women (50/group) received three cycles of either ORTHO TRI-CYCLEN Lo (NGM 180/215/250 microg/EE 25 microg), one of three cyclophasic regimens (NGM cycling 180-250 microg/EE 35 microg or 25 microg) or ORTHO TRI-CYCLEN. Among all five regimens, ovulation suppression, cycle control and safety were generally comparable. Presumed ovulation (serum progesterone levels >or=3 ng/mL during Days 19-21 of Cycle 3), occurred in 0/41 (0%) subjects on ORTHO TRI-CYCLEN Lo and 3/43 (7%) subjects on ORTHO TRI-CYCLEN. Breakthrough bleeding and/or spotting (BBS; % total cycles) was 17.2% for ORTHO TRI-CYCLEN Lo and 14.4% for ORTHO TRI-CYCLEN. The mean number of days of BBS/cycle for ORTHO TRI-CYCLEN Lo and ORTHO TRI-CYCLEN was 3.7 and 3.1, respectively, for those subjects with such bleeding. Thus, ORTHO TRI-CYCLEN Lo appears similar to ORTHO TRI-CYCLEN in inhibiting ovulation and providing cycle control.