A postcoital contraceptive with a lower incidence of nausea and vomiting than oestrogen-progestogen combinations would be a significant advance. During a nine-month period, 101 women were treated at the Margaret Pyke Centre in London with either an oestrogen-progestogen combination or with danazol. A comparison of the side effects of each drug is reported. Those treated with danazol were six times less likely to experience nausea and none vomited. With the exception of breast symptoms, other side effects were five times less common in women receiving danazol. These differences give danazol a clear advantage in terms of patient acceptability. Further experience will enable the efficacy of danazol to be evaluated and so determine whether this drug should become the preferred hormonal postcoital treatment.