Background. Host genetic predispositions may be important determinants of liver fibrosis in patients with chronic hepatitis C (CHC). The association between Interferon-? 4 (IFNL4) rs12979860 C>T polymorphism and risk of liver fibrosis in CHC is contradictory. Aim: To evaluate the impact of IFNL4 rs12979860 polymorphism on the risk of fibrosis in patients with CHC. Material and Methods: One hundred fifty patients with CHC aged 50 ± 11 years (89 females) were genotyped for IFNL4 rs12979860 using real time PCR. Fibrosis present in liver biopsies was assessed using the METAVIR score, comparing patients with either no fibrosis, mild fibrosis, or intermediate fibrosis (F0+F1+F2, n=96), with patients with severe fibrosis or cirrhosis (F3+F4, n=54). Results: In F0-F2 patients the distribution of rs12979860 genotypes was 22 CC, 57 CT and 17 TT, whereas in patients F3-F4 the distribution was 10, 29 and 15, respectively. No association between IFNL4 rs12979860 genotype and risk of fibrosis was observed in uni or multivariate analyses. Conclusions: IFNL4 rs12979860 C>T polymorphism is not associated with risk of liver fibrosis in this group of patients with CHC.Background. Host genetic predispositions may be important determinants of liver fibrosis in patients with chronic hepatitis C (CHC). The association between Interferon-? 4 (IFNL4) rs12979860 C>T polymorphism and risk of liver fibrosis in CHC is contradictory. Aim: To evaluate the impact of IFNL4 rs12979860 polymorphism on the risk of fibrosis in patients with CHC. Material and Methods: One hundred fifty patients with CHC aged 50 ± 11 years (89 females) were genotyped for IFNL4 rs12979860 using real time PCR. Fibrosis present in liver biopsies was assessed using the METAVIR score, comparing patients with either no fibrosis, mild fibrosis, or intermediate fibrosis (F0+F1+F2, n=96), with patients with severe fibrosis or cirrhosis (F3+F4, n=54). Results: In F0-F2 patients the distribution of rs12979860 genotypes was 22 CC, 57 CT and 17 TT, whereas in patients F3-F4 the distribution was 10, 29 and 15, respectively. No association between IFNL4 rs12979860 genotype and risk of fibrosis was observed in uni or multivariate analyses. Conclusions: IFNL4 rs12979860 C>T polymorphism is not associated with risk of liver fibrosis in this group of patients with CHC.