Objective: To assess the efficacy, acceptability and safety of triphasic oral contraceptive pill containing norgestimate 180/215/250 mg and ethinylestradiol 35 mg.Design and setting: Prospective, open-label, non-comparative, multicenter study in 409 centers in the Czech Republic. Methods: Body weight, blood pressure, bleeding pattern, headaches, nausea, breast tenderness, acne, pregnancies and side effects were monitored before the start of the treatment, after three and six cycles of oral contraceptive use. Liver function tests were carried out before and after the treatment. Results: Evaluating 26.432 cycles in 4.720 women the theoretical Pearl index was 0.15. There were no significant changes in body weight (61.45 kg before vs 61.58 kg after the treatment). There were clinically significant changes neither in the blood pressure nor in the liver function tests. Evaluating the bleeding pattern there were similar incidences of irregular bleeding/spotting befo- re the treatment and up to the third treatment cycle (16.15%, resp. 17.86%); then the incidence dropped down (8.41% after the third cycle). Amenorhea was very rare (0.41% resp. 0.35% up to, resp. after the third cycle). Decreasing incidences compared to pretreatment state were observed for headache, breast tenderness and acne. The effect on acne was remarkable (28.3% of women complaining of acne before the treatment vs 6.51% after the six treatment cycles). There were no serious adverse events observed during this study. Conclusion: Triphasic oral contraceptive pill containing norgestimate and ethinylestradiol pro- ved in a large multicenter study high both efficacy and acceptability.

        Key words: oral contraceptives, Norgestimate, Ethinylestradiol, efficacy, acceptability, bleeding pattern