We constructed an automated gravitational system to control fluid dynamics during hysteroscopic operations. The new system allows linear regulation of intrauterine pressure by varying the flow by simply changing the height of the fluid-filled bag above the patient. The outflow from the automated gravitational system is also driven by gravity. Between January 1994 and June 1995 we performed 88 hysteroscopic operations: 10 myomectomies, 8 endometrial ablations, 3 polypectomies, 3 lysis of synechiae, and 64 transcervical metroplasties. With the Vario Flow system we obtained good visualization, and all operations were performed adequately in one attempt. No surgical or general complications were encountered. We presume that patient safety will be increased further with the second version of this system, which has a built-in electronic fluid deficit-control system.