AIM: To assess the prevalence of advanced liver fibrosis (ALF) in human immunodeficiency virus (HIV), hepatitis C virus (HCV) and HIV/HCV patients using transient elastography, and to identify factors associated with ALF. METHODS: Between September 2008 and October 2009, 71 HIV mono-infected, 57 HIV/HCV co-infected and 53 HCV mono-infected patients on regular follow-up at our Center were enrolled in this study. Alcohol intake, the main parameters of liver function, presence of HCV-RNA, HIV-RNA, duration of highly active anti-retroviraltherapy (HAART) and CD4 cell count were recorded. ALF was defined as liver stiffness (LS) ≥ 9.5 kPa. To estimate liver fibrosis (LF) a further 2 reliable biochemical scores, aspartate aminotransferase platelet ratio index (APRI) and FIB-4, were also used. RESULTS: LS values of co-infected patients were higher than in either HIV or HCV mono-infected patients (χ 2M H = 4, P < 0.04). In fact, LS ≥ 9.5 was significantly higher in co-infected than in HIV and HCV mono-infected pa-tients (χ 2 = 5, P < 0.03). Also APRI and the FIB-4 index showed more LF in co-infected than in HIV mono-infect-ed patients (P < 0.0001), but not in HCV mono-infected patients. In HIV?HCV co-infected patients, the extent of LS was significantly associated with alcohol intake (P < 0.04) and lower CD4+ cell count (P < 0.02). In HCV pa-tients, LS was correlated with alcohol intake (P < 0.001) and cholesterol levels (P < 0.03). Body mass index, dia-betes, HCV-and HIV-viremia were not significantly cor-related with LS. In addition, 20% of co-infected patients had virologically unsuccessful HAART; in 50% compliance was low, CD4+ levels were < 400 cells/mm 3 and LS was > 9.5 kPa. There was no significant correlation between extent of LF and HAART exposure or duration of HAART exposure, in particular with specific dideoxynucleoside analogues. CONCLUSION: ALF was more frequent in co-infected than mono-infected patients. This result correlated with lower CD4 levels. Protective immunological effects of HAART on LF progression outweigh its hepatotoxic effects. AIM: To assess the prevalence of advanced liver fibrosis (ALF) in human immunodeficiency virus (HIV), hepatitis C virus (HCV) and HIV / HCV patients using transient elastography, and to identify factors associated with ALF. METHODS: Between September 2008 and October 2009, 71 HIV mono-infected, 57 HIV / HCV co-infected and 53 HCV mono-infected patients on regular follow-up at our Center were enrolled in this study. Alcohol intake, the main parameters of liver function, presence of HCV ALF was defined as liver stiffness (LS) ≥ 9.5 kPa. To estimate liver fibrosis (LF) a further 2 reliable biochemical scores RESULTS: LS values ​​of co-infected patients were higher than either either HIV or HCV mono-infected patients (χ 2M H = 4, P <0.04), aspartate aminotransferase platelet ratio index (APRI) and FIB- In fact, LS ≥ 9.5 was significantly higher in co-infected than in HIV Also APRI and the FIB-4 index showed more LF in co-infected than in HIV mono-infect-ed patients (P <0.0001), but In HCV co-infected patients, the extent of LS was significantly associated with alcohol intake (P <0.04) and lower CD4 + cell count (P <0.02). In HCV pa-tients, LS Body mass index, dia-betes, HCV-and HIV-viremia were not significantly cor-related with LS. In addition, 20% of co- infected patients had virologically unsuccessful HAART; in 50% compliance was low, CD4 + levels were <400 cells / mm 3 and LS was> 9.5 kPa. There was no significant correlation between extent of LF and HAART exposure or duration of HAART exposure, in particular with specific dideoxynucleoside analogues. CONCLUSION: ALF was more frequent in co-infected than mono-infected patients. This result correlated with lower CD4 levels. Pro tective immunological effects of HAART on LF progression outweigh its hepatotoxic effects.