BACKGROUND Reliable non-invasive methods for the evaluation of liver fibrosis are desirable, and the risk factors associated with fibrosis are not fully identified. METHODS A cross-sectional study of a cohort of 805 HIV-HCV-coinfected patients with active HCV replication, most (95.2%) of whom were intravenous drug users, was conducted. Liver fibrosis was measured by transient elastometry with cutoff values of 7.2 kPa (significant fibrosis), 9.4 kPa (advanced fibrosis) and 14.0 kPa (cirrhosis), and by liver fibrosis indexes (LFI; APRI, Forns and FIB-4). Available liver biopsies were also evaluated. RESULTS The prevalences of significant fibrosis, advanced fibrosis and cirrhosis were 55.8%, 38.4% and 23.5%, respectively. A number of parameters were associated both in the univariate and multivariate analyses with each of the diverse fibrosis groups; however, only six of them were predictive of all stages of fibrosis: heavy alcohol intake (odds ratio [OR] 3.37, 95% confidence interval [CI] 2.02-5.59; P < 0.001), duration of HCV infection (OR 1.13, 95% CI 1.07-1.19; P < 0.001), CDC category C3 (OR 1.80, 95% CI 1.07-3.02; P=0.026), anti-HCV treatment failure (OR 4.37, 95% CI 2.24-8.55; P < 0.001), thrombocytopaenia (OR 1.015, 95% CI 1.011-1.019; P < 0.001) and increased aspartate aminotransferase (1.006, 95% CI 1.0021-1.010; P = 0.004). Furthermore, 53%, 68% and 80% of patients with significant fibrosis, advanced fibrosis and cirrhosis, respectively, had increased measures on at least one of the LFI, with the Forns index being the most sensitive. Area under the receiver operating characteristic curves of elastometry to predict histological fibrosis was 0.83 (95% CI 0.76-0.90), 0.89 (95% CI 0.83-0.95) and 0.87 (95% CI 0.80-0.94) for Metavir score ≥ F2, ≥ F3 and F4, respectively. CONCLUSIONS Elastometry constitutes a useful tool in the diagnosis and follow-up of HIV-HCV-coinfected patients. Fibrosis is associated with diverse factors, some of them treatable or preventable, which need to be addressed considering the high prevalence and course of fibrosis in these patients.