Presented in this paper is the sterilization method of the assisted circulation unit. The method has been approved by stand testing and then applied for sterilizing the unit Ae, yeK-5 m when experimental implanting artificial heart. According to the method, ozone in concentration of 5 x 10(-3) moles/1 and with flow rate of 0,5 1/min is passed through an internal circuit of the unit during I h and 15 min. Control wash-out samples from lines have demonstrated complete sterility of the internal circuit. The method makes the sterilization process of such units much easier and may be recommended for clinical application.