The instruments used for psychological assessment have been under close scrutiny for many years. In particular, ethnic and racial minorities have pointed out that misapplication of instruments standardized to White middle-class norms can result in incorrect assessments. An analogous situation exists with IVDUs. In the work of the present authors with IVDUs, they were found to be a very diverse group. Contrary to common wisdom, they differ by race, ethnicity, age, and drug use profiles. However, their economic circumstances and social stigma make them a special case in terms of psychological assessment. Given the unique characteristics of IVDUs, it behooves researchers to carefully examine the standardized instruments that are available for psychological evaluation. Too often, measures standardized on White middle-class samples lack the value neutrality that makes them applicable across disparate groups. In addition, many such measures are designed with certain presumptions that do not necessarily hold true with this population (e.g., willingness and/or ability to communicate intimate information about one's feelings and psychological states). This article briefly describes some of the challenges encountered in examining standardized instruments for use in the study of IVDUs, their health psychology and AIDS-related behavior. Concerns with self-report biases, literacy, attentional focus, measurement constructs, and drug states confounding psychological states all pose challenges to psychological research with this heterogeneous population. While the need for direct intervention on the sexual and needle-sharing behaviors of IVDUs remains paramount in the combat against the spread of AIDS, researchers must also continue with the further development of basic measurement tools.(ABSTRACT TRUNCATED AT 250 WORDS)