OBJECTIVE: To investigate whether oral or vaginal administration of contraceptive hormones might affect antimüllerian hormone (AMH) levels. DESIGN: Prospective trial with women recruited by advertisement. Women who wished contraception were randomized between oral or vaginal estroprogestative contraception, and those who did not choose contraception were included in the control group. SETTING: Fertility clinic of a tertiary university hospital. PATIENT(S): Twenty-four young, healthy volunteer women with regular cycles who had received no hormonal contraception for at least 3 months before the study. INTERVENTION(S): Oral or vaginal estroprogestative contraception from day 5 to 25 of a menstrual cycle versus no contraception. MAIN OUTCOME MEASURE(S): Intercycle and intracycle variations of serum AMH levels in normally ovulating volunteers and following the initiation of oral or vaginal estroprogestative contraception. RESULT(S): Fluctuations of AMH levels observed during the menstrual cycle remained within cycle-to-cycle variability in cycling controls and in women receiving oral or vaginal contraception. CONCLUSION(S): Our findings confirm that AMH levels remain steady during the menstrual cycle and indicate that they are unaffected by exogenous sex steroids used for contraception whether administered orally or vaginally.