Muscle cramps are involuntary, painful, spasmodic contractions of the skeletal muscle. Although cramps are a common clinical complaint, their etiology and management have not been well established. Exercise-associated muscle cramps occur during or immediately following exercise, and they are associated with muscular fatigue and shortened muscle contraction. The main challenges for treating physicians are to identify whether the complaint represents a true muscle cramp as well as to rule out the presence of an underlying serious clinical condition. Muscle cramps may be a symptom of any of several conditions, including radiculopathies, Parkinson's disease, hypothyroidism, diabetes mellitus, vascular problems, electrolyte disorders, and metabolic myopathies. Cramps also may occur as a side effect of certain drugs (eg, lipid-lowering agents, antihypertensives, beta-agonists, insulin, oral contraceptives, alcohol). Most athletes who experience exercise-associated muscle cramps are healthy individuals without systemic illness. Therapy should focus on preventing premature fatigue by means of appropriate nutrition and adequate training.