Hepatitis C (HCV) and HIV have common modes of transmission but information about HCV transmission risk, prevention, and treatment among persons with coinfection is lacking. The Medical Monitoring Project produces nationally representative estimates describing adults with diagnosed HIV in the United States. Using medical record data recorded during 6/2013-5/2017, we identified persons with detectable HCV RNA documented during the past 24 months. Among persons with coinfection, we described HCV transmission risk factors and receipt of HCV prevention services during the past 12 months and prescription of HCV treatment during the past 24 months. Overall, 4.9% had documented active HCV coinfection, among whom 30.2% were men who have sex with men (MSM), 6.7% reported injection drug use, and 62.1% were prescribed HCV treatment. Among MSM, 45.5% reported condomless anal sex and 42.3% received free condoms. Among persons who used drugs, 30.8% received drug or alcohol counseling, and among persons who injected drugs, 79.2% received sterile syringes. Among persons with HIV/HCV coinfection, recent drug injection was uncommon and most received sterile syringes. However, 1 in 3 were MSM, of whom half reported recent HCV sexual transmission risk behaviors. More than one-third of those with coinfection were not prescribed curative HCV treatment.