A Cochrane review included 22 studies with a total of 12 400 subjects. Pericoital use of levonorgestrel (LNG) on a regular basis to prevent pregnancy was assessed in 15 trials. Pericoital LNG was reasonably efficacious and safe. The pooled Pearl Index for the 0.75 mg dose of LNG was 5.4 per 100 woman-years (WY) (95% CI 4.1 to 7.0; 11 trials). The pooled Pearl Index for all doses of LNG was 5.0 per 100 WY (95% CI 4.4 to 5.6). Other hormonal drugs appeared promising but were assessed only in 7 trials and were not studied extensively. Most women liked the pericoital method in spite of frequent menstrual irregularities.