Thesis (M.A.)--Boston University / Cocaine use among opioid dependent persons is common, with an estimated 40 to 70% of those seeking treatment for opioid dependence, also using cocaine (Sullivan et al., 2011 ). The effects of cocaine use on treatment outcomes for those seeking medication assisted treatment (MAT) for opioid dependence are not well understood. Buprenorphine, prescribed under the brand name Suboxone, has recently emerged as a convenient, effective method of MAT. The Facilitated Access to Substance Abuse Treatment with Prevention And Treatment of HIV (FAST PATH) program at Boston Medical Center, is a research study to provide substance abuse treatment along with primary care and HIV risk-reduction counseling to those afflicted with these epidemics. The objective of this study was to determine the association of cocaine use with treatment retention and opioid abstinence at six months for patients receiving buprenorphine in the FAST PATH program. A prospective cohort study was conducted on 116 patients enrolled in the FAST PATH program through 02/01/2012. Assessments were conducted at baseline and six months to evaluate the association between baseline cocaine use and treatment retention as well as opioid abstinence at six months. Baseline cocaine use was measured by either any urine toxicology screen positive for cocaine prior to study enrollment or 30 day self-reported cocaine use on the initial assessment. Of the 116 participants, 39% were positive for cocaine use at baseline and 52% were HIV positive. Baseline cocaine use had no effect significant on treatment retention or opioid abstinence at six months. Among all the participant characteristics measured, there were no significant differences between the cocaine positive (n=45) and cocaine negative (n=71) groups. In adjusted analysis, age was the only covariate which was significant at predicting the odds of treatment retention or opioid abstinence with a 1.11 (p-value = 0.0003) and 1.08 (p-value = 0.02) greater odds of each, respectively. Although cocaine use did not affect the dependent variables, integrated substance abuse and primary care clinics utilizing buprenorphine are a rich area of future research. Specifically, subsequent studies should determine how varied groups of opioid dependent persons perform within this framework, and the underlying characteristics moderating their outcomes.