Some observations were made that fetal penile erection can occur even during the intrauterine life. The current study was undertaken in order to determine how frequently and to what extent this may occur. In the course of the prenatal ultrasound examination the author identified the genitalia of 250 male fetuses during the 3rd trimester. Penile erection was noted in 9 (3.6%) fetuses. The observed erections lasted 8-10 minutes. While in the state of erection, both the length and diameter of the penis increased. Its length exceeded the diameter of the scrotum. Fetal penile erection appears to be the evidence of an appropriate genital development and its adequate hormonal and neurogenic supply. Therefore the occurrence of erection presumably may be a positive sign of fetal well being.