A new gearing approximator for microsurgical vascular anastomoses is described. A highly precise and smoothly working robust gearing in connection with an asymmetrically notched key allows quick application of the approximator and an exactly adjustable interclip distance. By means of a combined handling and gearing screw and exchangeable 30 degrees-angled clips the instrument can easily be applied in narrow operating fields, and it can be handled under vision through the operating microscope without change in magnification adjustment. A quickly increasing platelt aggregation at the suture line and an early "slow flow" can be achieved by gradual opening of the clips. The ease of approximator application may contribute to shortening operation times.