A sample of 196 general medical patients with multiple unexplained somatic complaints was used to compare the performance (sensitivity and specificity) and positive and negative predictive values for the published screening indexes for somatization disorder. This study shows similar performances for both the DSM-III-R and the Swartz et al. screening indexes for somatization disorder with use of DSM-III-R diagnostic criteria. By use of Receiver Operating Characteristic (ROC) curve analysis, graphs of achievable sensitivity and specificity through the range of possible symptom thresholds allow for a more informed decision to be made concerning which screening index to use at a given symptom threshold. Positive predictive values for screening indexes ranged from 68% to 79%, and negative predictive values ranged from 72% to 81%. Use of a screening index is suggested in medical patients with unexplained complaints and in patients seen in the consultation-liaison (CL) setting.