Background Significance of steatosis in HIV-HCV coinfection remains controversial. Aim To compare the prevalence and predictors of hepatic steatosis between HIV-HCV and HCV patients matched for steatosis known determinants. Methods A total of 564 HCV-naive patients undergoing liver biopsy were studied: 137 with HIV-HCV coinfection and 427 with HCV monoinfection, among whom 137 were matched for age, gender, body mass index and HCV genotype. Results Steatosis of any grade (67.1% vs. 41.6%, P < 0.0001), mixed steatosis (55.4% vs. 21.1%, P < 0.0001), severe histological activity (A2-A3: 78.1% vs. 55.5%, P < 0.0001) and severe fibrosis (F3-F4: 33.1% vs. 15.3%, P < 0.0001) were significantly more common in coinfected than in matched monoinfected patients. In multivariate analysis, steatosis was associated only with severe histological activity [odds ratio (OR): 3.1 (95% CI: 1.3-7.1)] in coinfected patients and with elevated body mass index [OR; 1.3 (1.1-1.5)], HCV genotype 3 [OR: 5.6 (2.3-13.9)], severe histological activity [OR: 3.1 (1.3-7.3)] and severe fibrosis [OR: 4.7 (1.3-17.3)] in monoinfected patients. Conclusions Steatosis is significantly more common and severe in HIV-HCV coinfected than in HCV monoinfected French patients, even after matching for body mass index and HCV genotype. Steatosis is associated only with severe histological activity in coinfected patients and with previously reported factors in monoinfected patients, thus suggesting different underlying mechanisms.