While hepatitis C virus (HCV) infection seems to be expanding among HIV-infected men who have sex with men (MSM), the rate of coinfection in intravenous drug users (IDU) is assumed to remain constant. We evaluated the serial prevalence of HIV/HCV coinfection across all risk groups for HIV infection in Spain. We used data from 7045 subjects included in the multicentre, prospective Spanish Cohort of Adult HIV-infected Patients (CoRIS) between 2004 and 2011. We analysed risk factors for HIV/HCV coinfection by logistic regression analyses. The prevalence of HIV/HCV coinfection decreased from 25.3% (95% CI, 23.1-27.5) in 2004-2005 to 8.2% (95% CI, 6.9-9.5) in 2010-2011. This trend was consistently observed from 2004 to 2011 among all risk groups: IDU, 92.4% to 81.4%; MSM, 4.7% to 2.6%; heterosexual men, 13.0-8.9%; and heterosexual women, 14.5-4.0% (all P < 0.05). Strongest risk factors for HIV/HCV coinfection were IDU (OR, 54.9; 95% CI, 39.4-76.4), birth decade 1961-1970 (OR, 2.1; 95% CI, 1.1-3.7) and low educational level (OR, 2.4; 95% CI, 1.6-3.5). Hence, the prevalence of HIV/HCV coinfection decreased in Spain between 2004 and 2011. This decline was observed across all risk groups and is likely to be explained by a declining burden of HCV in the general population.