Objective : To evaluate luteinizing hormone (LH) in patients with infertility and recurrent spontaneous abortion. Material and Method: LH was tested by solid phase immunoradiometric assay based on monoclonal and polyclonal anti-LH antibodies. Results: Of 100 infertile patients, the number of less than 5 mIU/ml, 5$sim$10 mIU/ml, greater than 10 mIU/ml in LH level was 67 (67%), 22 (22%), 11 (11%), respectively. Of 100 patients with recurrent spontaneous abortion, the number of less than 5 mIU/ml, 5$sim$10 mIU/ml, greater than 10 mIU/ml in LH level was 79 (79%), 18 (18%), 3 (3%), respectively. There was a significant difference between patients with infertility and recurrent spontaneous abortion only in the group with LH level greater than 10 mIU/ml (p=.0325). Conclusions: High LH in the follicular phase is known to decrease pregnancy rate and increase abortion rate. But in this study the incidence of high LH in patients with recurrent spontaneous abortion was low. On the contrary, there was a significant increase of LH in infertile patients. So recurrent spontaneous abortion does not seem to be related to high LH level.