Effective cycle control was demonstrated based on two multicenter, 2‐year studies of the triphasic oral contraceptive (OC) agent containing the new progestin norgestimate. The estrogen in this OC is ethinyl estradiol. These open‐label Phase III studies were conducted in the United States by 33 investigators at 33 sites who treated a total of 1,783 subjects, healthy women 17 to 38 years of age with menstrual cycle characteristics considered to be within the normal range. The norgestimate/ethinyl estradiol preparation was taken for up to 24 cycles. Follow‐up information was collected 3 to 4 months post‐treatment. Bleeding pattern analyses were based on 27,970 valid cycles. Normal cyclic bleeding patterns were experienced by most of the women during the study; only minimal and statistically and clinically insignificant variations in menstrual flow, dysmenorrhea, and premenstrual tension occurred. There was a low incidence of failed withdrawal bleeding in single cycles (<1.0% after cycle 6). There were no cases of amenorrhea, defined as two consecutive cycles of missed withdrawal flow. The incidence of breakthrough bleeding or spotting was highest during the initial treatment cycles and diminished with continued use of the formulation. The mean incidence of breakthrough bleeding was 2.36% in cycles 13 to 24. Apart from somewhat higher initial percentages among women new to oral contraception, the pattern of midcycle bleeding or spotting was similar to that of all women studied. Effective long‐term cycle control was demonstrated in women who used this