This chapter, written for undergraduate medical students and post-graduate doctors in training, presents information on how to manage mania — a case which they are likely to encounter in the future in a general practice setting. It presents the case of a 35-year-old man who had a 2-month history of headaches and left eye pain. On questioning him further, the general practitioner (GP) finds out that he has felt more irritable recently, with increased energy and racing thoughts. 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.