We have previously presented data to show that in patients who had in-vitro fertilization (IVF)-embryo transfer using ovarian stimulation involving the luteal phase leuprolide acetate--human menopausal gonadotrophin (HMG) regimen, poor pregnancy results ensued if either the endometrial thickness was < 10 mm or a homogeneous hyperechogenic sonographic pattern was present immediately prior to taking a human chorionic gonadotrophin (HCG) injection. There were only 15 cases with this hyperechogenic type endometrium (and no pregnancies). The purpose of the present study was to evaluate the influence of a hyperechogenic endometrium when the endometrial thickness was > or = 10 mm, in a more extensive series, in women having IVF-embryo transfer using the same ovarian stimulation regimen. A total of 273 consecutive cycles, where endometrial thickness was > or = 10 mm, were evaluated (not including the 85 cycles previously reported). Of 22 patients with the hyperechogenic pattern, one achieved a chemical pregnancy (beta-HCG > 500 mIU/ml) and none achieved clinical pregnancies (ultrasound confirmation). In contrast, 67 of 251 (26.7%) patients conceived with other echo patterns (chi 2 analysis = 5.9, df = 1, P = 0.01). These data thus confirm, in a larger series, the negative influence of this type of echo pattern on subsequent pregnancy rates following the luteal phase leuprolide acetate--HMG ovarian stimulation regimen.