The ectopic pregnancy is a relatively common condition in the south African black patients. The beta-specific subunit radioimmunoassay for human chorionic gonadotrophin (HCG) was utilized in procuring information in our series of 30 patients. Levels of the hormone were significantly lower when compared to normal gestation of similar duration, never exceeding 2000 mIU/ml. The clearance rate of HCG following normal vaginal delivery was about 24 h and less variable than that of ectopic gestation. The half-life clearance rate of HCG in the ectopics could be divided into three phases, suggestive of HCG compartmentalization. The possible buffering effect of this hormone in the maintenance of the receptor-saturated pregnancy is discussed. The possibility that the HCG produced by the normal pregnancy is dissimilar to that of ectopic is speculated upon.