['To evaluate, retrospectively, the roles of endogenous and exogenous luteinising hormone (LH) activity on live birth rate in ovulation induction cycles.', 'Associations between LH activity at baseline, end of stimulation and live birth rate were analysed in relation to patient characteristics, baseline and end of stimulation variables in WHO group II anovulatory women (n = 155) stimulated with recombinant follicle-stimulating hormone (rFSH) or highly purified human menopausal gonadotrophin (HP-hMG). HP-hMG provides FSH and exogenous LH activity mainly in the form of human chorionic gonadotrophin (hCG).', 'Serum LH concentrations at baseline or end of stimulation were not predictive of live birth rate in the rFSH group (n = 79) or HP-hMG group (n = 76). Serum hCG concentration at end of stimulation was a significant positive predictor in HP-hMG-treated women. Other variables were not independently predictive of live birth in either of the groups, except for a negative association between serum FSH concentrations at the start of stimulation and live birth in the rFSH-treated group.'] Is exogenous hCG activity , but not endogenous LH activity , positively associated with live birth rates in anovulatory infertility?