This chapter, written for undergraduate medical students and post-graduate doctors in training, presents information on how to manage muscle pain — a case which they are likely to encounter in the future in a general practice setting. It presents the case of a 65-year-old woman who has been suffering from general pain and stiffness, particularly in her thighs and both shoulders. She reports that these symptoms started quite suddenly and that, in the morning when she wakes up, she has really bad and painful generalized stiffness, making it hard to move and that this stiffness lasts for at least an hour before easing. 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.