Having observed a three-fold difference in the prevalence of significant symptoms of depression among four race-gender groups of elderly adults attending an urban primary care practice, we investigated the extent to which these differences might be explained by variability in the measurement properties of the Centers for Epidemiologic Studies depression scale (CES-D). Although the internal consistency of the CES-D was acceptable for all groups, 5% of our patients were excluded for inability to complete the minimum required number of CES-D items, and nearly 40% of patients required response imputation for the allowable one to four items that they could not answer. Imputation was most frequently required for items tapping positive affect. Principal components factor analysis was performed separately for respondents answering all items and for respondents with imputed values. In both analyses we found important race-gender differences in factor structure. Moreover, the factor structure for those with imputed values was markedly different from that of respondents answering all items, including a dissolution of the positive affect dimension. Neither the race-gender differences in factor structure nor the differences among those with and without imputed data were resolved by eliminating respondents with poor education, cognitive impairment, or alcoholism, or by varying the assumptions for data imputation. However, the disparities in factor structure were essentially resolved by eliminating five CES-D items, suggesting the need to modify the CES-D in populations like ours. Although eliminating these five items results in a more pure factor structure, it does not resolve the differences in prevalence of depressive symptoms. These differences may, however, be partially due to differential response tendencies among the race-gender groups.