The American Journal of Drug and Alcohol Abuse, 34: 329–337, 2008 Copyright © Informa Healthcare USA, Inc. ISSN: 0095-2990 print / 1097-9891 online DOI: 10.1080/00952990802010876 HIV Risk and History of STDs in MCMI-III Psychopathology Subgroups of Comorbid Substance Abusers Robert C. McMahon, Ph.D., 1 Robert M. Malow, Ph.D., 2 Jessy Devieux, Ph.D., 2 Rhonda Rosenberg, Ph.D., 2 and Terri Jennings, Ph.D. 2 1 University of Miami, Coral Gables, Florida, USA 2 Florida International University, Miami, Florida, USA Abstract: The purpose of this investigation is to investigate HIV risk-related attitudes, beliefs, expectancies, behaviors, and histories of lifetime sexually transmitted diseases in the Millon Clinical Multiaxial Inventory III (MCMI-III) defined psychopathology clus- ter subgroups. Hierarchical agglomerative cluster analysis, using Ward’s method, was employed that led to identification of high (n = 37), medium (n = 132), and low (n = 28) MCMI-III psychopathology cluster subgroups. Members of the low psychopathology subgroup demonstrated significantly higher levels of knowledge about HIV and AIDS and less anxiety about HIV infection than high and moderate psychopathology sub- groups. The high psychopathology subgroup reported greater importance of approval of condom use by partners but less sexual self-efficacy than the moderate psychopathology subgroup. This high pathology group revealed less favorable condom attitudes than did the low psychopathology subgroup and a significantly higher percentage of unprotected vaginal sex acts in the past 6 months than did members of the other two subgroups. A comparatively low rate of lifetime syphilis was reported in the low psychopathology subgroup (all ps < .05). Results are discussed in the context of a growing literature indi- cating distinctive treatment needs among members of high psychopathology subgroups of drug treatment participants. Keywords: HIV risk, psychopathology subgroups There has been increasing interest in personality disorders and other psychi- atric conditions among substance dependent individuals that might elevate risk for HIV infection and influence response to HIV prevention intervention. This study was funded in part by Grant RO1AA12115 from the National Institute on Alcohol Abuse and Alcoholism to Dr. Malow. Address correspondence to Robert C. McMahon, University of Miami, P.O. Box 248065, Coral Gables, FL 33124. E-mail: mcm7798@bellsouth.net 329