Although somatic complaints are the predominant reason for seeking general medical care, their etiology and prognosis remain poorly understood. In a random sample of the records of all patients visiting an urban primary care clinic during four 1-month periods, 289 patients had one or more somatic symptoms, a total of 433 symptoms. Using explicit criteria, physician raters classified nearly half (48%) of the symptoms as either psychiatric or idiopathic in etiology. Reviewing follow-up notes for 12 months after the index visit, raters found that at least one-fourth of the symptoms persisted. Independent predictors of symptom persistence were prior visits for the same symptom, symptom type (i.e., headache or back pain), male gender, and greater medical comorbidity (i.e., seven or more medical diagnoses). Developing better management strategies for prevalent, medically unexplained, persistent somatic symptoms is a health care priority.