Follicle puncture with oocyte harvest or ovarian inspection for an early corpus luteum was carried out in 13 patients undergoing laparoscopy during routine infertility workup. Laparoscopies were carried out 28 to 38.5 hours after the onset of the luteinizing hormone surge so that there would be a concentration of data around the expected time of ovulation. A rapid luteinizing hormone assay was used. All the corpora lutea were found 38 hours or more after the onset of the luteinizing hormone surge. Between 28 and 38 hours after the onset of the surge, intact follicles containing oocytes in various stages of maturation were found.