ObjectivePoland has a restrictive abortion law. Emergency contraception (EC) is expensive and available only on prescription, which is not easily obtainable in public health care. We aimed to identify the main reasons for EC requests, observed failure rates and the type and incidence of adverse effects. DesignProspective single-center observational study. PopulationA cohort of women living in Warsaw, who requested EC. MethodsData were collected via a questionnaire completed by healthcare providers prescribing EC, and included age, date of the request, previous EC use, time from intercourse to clinic visit and day of menstrual cycle on which intercourse took place. Main outcome measuresReason for EC request, time lapse between unprotected intercourse and EC use, age of women requesting EC, reported cases of pregnancy. ResultsA total of 4655 women requested EC. Of these 62.9% (n=2928) were 25years old. During follow up, 0.75% (31 individuals) became pregnant. Adverse effects of hormonal EC were rare and mild. The main reason for requesting EC was problems associated with condoms (63.2%, n=2609). The mean interval between unprotected intercourse and EC use was 21.2h, but 26.7h when EC failed (n.s.). Considering intake within and after 24h, the difference was significant (p<0.05). ConclusionsWomen living in Warsaw seeking EC used the EC product very soon after unprotected intercourse, and this was probably one of the most important reasons for the low pregnancy rates in the studied population.