This report describes a case of a collegiate baseball player who presented with 3 weeks of worsening right shoulder pain and mild swelling and faint discoloration of the right arm and hand. He was found to have a nonocclusive clot on his brachial vein and was treated with anticoagulants. This was his second lifetime thrombosis. A hematologic workup revealed no evidence of a hereditary origin, and thrombosis was believed to be related to recent exertion (baseball throwing). Upper extremity deep vein thromboses are extremely uncommon. However, because they can have potentially life-threatening consequences, deep vein thromboses must be on the differential for any athlete who presents with increased pain, swelling, or discoloration of an extremity.