We report a previously well 9-year-old boy who presented with an acutely swollen left arm after horse riding. Left subclavian vein thrombosis was demonstrated by MR venography but there was no evidence of an underlying anatomical abnormality. The child was successfully treated with catheter directed thrombolysis and anticoagulation with intravenous unfractionated heparin and warfarin. We have identified 75 previously published case reports of effort-induced upper extremity deep vein thrombosis (UEDVT) and surveyed patient characteristics and precipitating activities. In this case and literature review, we demonstrate that individuals with effort-induced UEDVT show demographic characteristics and presenting features that are distinct from other patient groups with venous thromboembolic disease. We also highlight the difficulties in counselling affected individuals about modifying occupational and recreational activities to minimise the risk of recurrent thrombosis.