This review discusses the available data reporting the efficacy of emergency contraceptive treatment with the Yuzpe regimen (0.2 mg of ethinyl oestradiol in combination with either 2.0 mg of norgestrel or 1.0 mg of levonorgestrel) and evaluates the true effectiveness in preventing pregnancy. A literature review was completed for reports including women treated with the Yuzpe using a MEDLINE search for articles published since 1970 and by reviewing the secondary reference lists of these manuscripts. Expected pregnancy rates for each study population were calculated using published conception rate estimates. Seven published studies provided adequate data to assess accurately efficacy of the Yuzpe regimen in preventing pregnancy after unprotected intercourse. Of 2871 women treated, 54 (1.9%, 95% confidence intervals (CI) 1.4-2.4) became pregnant. By calculating the expected pregnancy rates using two different methodologies, the Yuzpe regimen decreased the observed number of pregnancies by 70.0% (95% CI 63.3-76.7) and 77.2% (95% CI 71.5-82.8). Emergency contraception with the Yuzpe regimen is an effective form of contraception to prevent unwanted pregnancy after unprotected intercourse.