OBJECTIVE To evaluate the effect of exogenous luteinizing hormone on IVF/ICSI success. DESIGN Retrospective clinical study. SETTING 2nd Department of Gynaecology and Obstetrics, Medical Faculty and L. Pasteur University Hospital Kosice, Slovak Republic. METHODS Individual parameters and clinical pregnancy rate of 232 IVF/ICSI cycles were compared in dependence on stimulation protocol (pure rFSH vs. rFSH and 75 IU rLH from S7). RESULTS There was no statistically significant difference in IVF/ICSI success between individual groups and subgroups, but we demonstrated the increase in clinical pregnancy rate per ET in agonist cycles group with exogenous LH activity totally above 11% (27.6% vs. 38.6%), in patients under 35 years above 12% (30.4% vs. 42.6%) and in patients over 35 years above 14% (16.7% vs. 30.8%). In antagonist cycles group there was demonstrated the increase in clinical pregnancy rate only in women over 35 years - above 14% (13.3% vs. 30.8%). CONCLUSIONS Despite of negative statistical analyses, from the clinical point of view we can strongly recommend the LH addition during COH, especially in agonist cycles and in older women.