Objective We documented the prevalence distribution and correlates of hepatitis C virus (HCV) infection among urban homeless adults. and multiple-drug injection. Among lifetime drug injectors impartial predictors of HCV contamination included older age prison history and no history of intranasal cocaine use. Among reported non-injectors predictors of HCV contamination included older age less education use of non-injection drugs and three or more tattoos. Sexual behaviors and snorting or smoking drugs experienced no impartial relationship with HCV contamination. Among HCV-infected adults nearly half (46.1%) were unaware of their contamination. Conclusions Despite the high prevalence of HCV contamination nearly half of the cases were hidden and few experienced ever received any HCV-related treatment. While injection drug use was the strongest impartial predictor patterns of injection drug use non-injection drug use prison stays and multiple tattoos were also impartial predictors of HCV. Findings suggest that urgent interventions are needed to screen counsel and treat urban homeless adults for HCV contamination. The hepatitis C computer virus (HCV) is the most common chronic blood-borne viral contamination in the United States. Beginning HSP70-1 in 1988-1994 1 the National Health and Nutrition Examination Survey (NHANES) a survey of U.S. households began estimating prevalence rates Linifanib (ABT-869) for hepatitis C contamination in the U.S. general populace for those aged 6 years and older. The most recent national prevalence estimate (based on the 1999-2002 NHANES) was 1.6% or about 4.1 million people.2 The primary identified means of transmission was through injection drug use. Regrettably the NHANES excluded large groups at high risk for HCV contamination. A recent article suggested that if high-risk groups that were missed or underrepresented in NHANES (i.e. homeless or incarcerated people Veterans health-care workers and those on long-term dialysis)3 had been included a conservative estimate of HCV in the U.S. would have been somewhat higher at 2.0% or about 5.2 million people.4 5 These understudied populations that constitute a significant reservoir of HCV infection can provide additional insight into the extent and correlates of HCV infection. Recent studies suggest that homeless adults in urban areas are at particularly high risk for hepatitis C contamination (19%-69%) due to high rates of risky injection drug use.6-13 Unfortunately these studies have usually been based on convenience clinical or subgroup samples and findings may not generalize beyond the groups studied.14 We documented the prevalence distribution and risk factors for HCV infection based on a probability sample of homeless adults. This study fills an important space in the literature by using a large representative sample of inner-city homeless adults to generate a more accurate estimate of HCV contamination in an urban homeless adult populace. Further we documented the high prevalence of “hidden” (i.e. participants were unaware of their contamination status) HCV contamination in this group and the current unmet need for HCV screening and HCV-specific health services. Findings will inform future intervention and treatment programs aimed at preventing exposure to and transmission of HCV among homeless people and the general population. METHODS For the University or college of California at Los Angeles (UCLA)/Alcohol Research Group (ARG)/RAND Corporation Homeless Hepatitis Study (known as the UCLA/ARG/RAND Homeless Hepatitis Study) a community-based probability sample of homeless Linifanib (ABT-869) adults was recruited from your Skid Row area in downtown Los Angeles (LA) from June 2003 to February 2004. Target populace The target populace was adults who experienced homelessness during the previous night. To be eligible participants had to be ≥18 years of age; have spent the previous night either (1) in a general Linifanib (ABT-869) public or private shelter or (2) around the streets (i.e. in a general public or private place not designed for or ordinarily used as regular Linifanib (ABT-869) sleeping accommodations for humans);15 be English-speaking; and demonstrate cognitive competence assessed as needed.16 Design We adapted the service-sector approach to probability sampling which has been used successfully in previous work with homeless populations17-19 and which reportedly represents the great majority of.