Fourteen common physical symptoms are responsible for almost half of all primary care visits. Only about 10% to 15% of these symptoms are found to be caused by an organic illness over a 1-year period. Patients with medically unexplained symptoms are frequently frustrating to primary care physicians and utilize medical visits and costs disproportionately. This paper will review the relationship between psychological distress and the decision to seek medical care for common physical symptoms such as fatigue and headache. Evidence will be presented demonstrating that an increasing number of medically unexplained symptoms over a patient's lifetime correlate linearly with the number of anxiety and depressive disorders experienced, the score on the personality dimension of neuroticism, and the degree of functional impairment. Several scales measuring somatization and hypochondriasis are recommended for primary care and medical specialty patients.