['To elucidate the LH receptor (LHR) expression patterns in human granulosa cells (GCs) from antral to preovulatory stages, and to investigate a correlation to oocyte function.', 'Luteinized preovulatory GCs were obtained from preovulatory follicles aspirated during IVF (≥ 17 mm). The GCs from small- (<10 mm) and medium-sized (10-15 mm) follicles were obtained during in vitro maturation (IVM) procedures. Cumulus GCs were obtained during oocyte denudation for intracytoplasmatic sperm injection (ICSI) procedures (IVF).', 'Referral center.', 'Seventy IVF patients and 20 IVM patients.', 'GC collection.', 'The LHR expression levels in mural and cumulus GCs of different follicular sizes and their correlation to oocyte outcome.', 'The LHR expression increased with follicle size and was higher in mural GCs compared with cumulus cells. The LHR expression in cumulus GCs from preovulatory follicles was higher in metaphase II (MII) oocytes than in metaphase I or germinal vesicle oocytes (IVF). Unexpectedly, higher expression of LHR in cumulus GCs of MII oocytes correlated with decreased fertilization rates.'] Is high expression of luteinizing hormone receptors messenger RNA by human cumulus granulosa cells in correlation with decreased fertilization?