Abstract: Filling device and method for use in manufacturing of gel filled prostheses which provides fast and accurate filling of prosthesis shells without deterioration of the gel or induction of air into the prosthesis. The filling method utilizes a dual port cannula for penetrating a preslit fill port on a prosthesis shell, the cannula having one port coupled through a flexible tube to a peristaltic pump supplied with gel under pressure, and a second port coupled through a flexible tube to a vacuum system. The cannula and prosthesis shell being filled are supported on a scale, with the flexible tubes being disposed so that pressure variations in the tubes do not effect the scale readings.