This chapter, written for undergraduate medical students and post-graduate doctors in training, presents information on how to manage arm Injury — a case which they are likely to encounter in the future in a general practice setting. It presents the case of a 30 years old man who injured his arm the previous day getting out of his articulated lorry. On examining the patient's arm, the general practitioner (GP) finds that the patient is tender just distal to the lateral condyle of his humerus. There is no evidence of bruising or swelling. The chapter provides details of the patients' medical history and the key findings of clinical examination, together with initial investigation results data for evaluation, and helps them develop their skills of clinical reasoning. Key questions then prompt the student to evaluate the patient, and reach a decision regarding their condition and the possible treatment plan.