Three definitions of somatization were operationalized: (a) high levels of functional somatic distress, measured by the Somatic Symptom Index (SSI) of the Diagnostic Interview Schedule; (b) hypochondriasis measured by high scores on a measure of illness worry in the absence of evidence for serious illness; and (c) exclusively somatic clinical presentations among patients with current major depression or anxiety. Of 685 patients attending two family medicine clinics, 26.3% met criteria for one or more forms of somatization. While DSM-III somatization disorder had a prevalence of only 1% in this population, 16.6% of the patients met abridged criteria for subsyndromal somatization disorder (SSI 4,6). Hypochondriacal worry had a prevalence of 7.7% in the clinic sample. Somatized presentations of current major depression or anxiety disorder had a prevalence of 8%. The three forms of somatization were associated with different sociodemographic and illness behavior characteristics. A majority of patients met criteria for only one type of somatization, suggesting that distinct pathogenic processes may be involved in each of the three types.