The importance of wound drainage in casualty and plastic surgery is unquestioned. The most common form is suction drainage. This involves the disadvantage that the drain can become attached to the tissue by suction, stopping the flow and blocking the drain. In addition, the secretion reservoir must be made of rigid material, which means large package sizes are inevitable. Encouraged by our knowledge of silicone drains, we carried out a study comparing silicone drains (without vacuum) and PVC drains (with vacuum suction). Electron-microscope studies of the PVC drains used for suction drainage revealed adhesion of wound secretion and cell detritus to the inner wall and the drainage perforations after less than 24 h. No occlusion and almost no adherence was observed with silicone gravity drains. When compared in clinical use for joint drainage, neither system had any severe complications. Removal of gravity drains was considerably less painful than withdrawal of suction drains. In soft tissue drainage the volume of secretion drained off was more constant and obviously larger with gravity drainage. From these results we conclude that gravity drainage can replace suction drainage to considerable advantage.