The authors report 7 patients with thromboses in the upper extremity resembling Paget-Schroetter syndrome. According to their case histories, all patients had a temporal and causal relationship between partially unusual sports activities and the genesis of the thrombosis. The cause of this condition is a strain on the subclavian and axillary veins by retroversion or hyperabduction of the arm. This can entail microtraumatizations of the venous intima, consequently leading to a consecutive local activation of coagulation and to a possible thrombosis of the vessel. A mechanical compression of the vein by adjoining bone, ligament, and muscle structures can intensify the effects. Further primary diseases and risk factors as secondary causes for thromboses where taken into consideration when examining the patients. The Paget-Schroetter syndrome should be considered as a possible cause for unspecified trouble in the upper extremity reported by athletes. If such prolapses occur, they can be categorized as accidents by private and statutory insurance companies that cover accidents.