The endometrium of a series of 190 in vitro fertilization patients was investigated by transvaginal ultrasound. The endometrial pattern was related to the likelihood of implantation. No such relationship was found for the thickness of the endometrium. There was not a strong correlation between the endometrium and hormonal values. However, three endometrial patterns were detected after hormonal stimulation. The predominant pattern consisted of an outer hyperechogenic layer and an inner hypoechogenic layer. This pattern correlated in a positive fashion with subsequent implantation. It is concluded that the texture of the endometrium at the time of ovum pickup has a prognostic value for the likelihood of implantation to occur.