The plasma concentrations of the beta subunit of human chorionic gonadotropin (beta-hCG), pregnancy-specific glycoprotein, and progesterone were measured in 37 pregnancies after in vitro fertilization. Twenty-one pregnancies ended with delivery, 9 as clinical abortions, and 7 as biochemical abortions. To predict the pregnancy outcome as early as possible, we designed a prediction graph by calculating a "cutoff line" using discriminant analysis and prediction bands up to 95% probability. This prediction graph can help in the estimation of the probability of pregnancy outcome with satisfactory reliability by determination of beta-hCG only.