Abstract: An apparatus for achieving and maintaining penis erection--based on the effect of a reduced air pressure on the external surface of the penis comprises a transparent tube (19) provided with a head (17) with automatic regulator (1-4) of air discharge from the tube and a vacuum pump (15). When the penis is inserted into the tube (19) and when the bellows (14) of the pump (14) are periodically depressed, the penis will, under the effect of a reduced air pressure, reach its erection. By shifting a lever (20) in the F direction, an elastic ring (9) will be slipped from the neck of the tube (19) onto the base of the penis in erection and the erection will be maintaining during the intercourse. Just before the ejaculation, the elastic ring (9) will be quickly disconnected and the semen will be normally expelled before the penis is taken out of the vagina.