The impact of hepatic steatosis on interferon therapy for patients with chronic hepatitis C (CHC) has been associated with single-nucleotide polymorphisms (SNP) of IL28B, patatin-like phospholipase domain-containing protein 3 (PNPLA3), and low-density lipoprotein (LDL) receptor. Whether this holds true for Japanese patients, however, remains unresolved. The present study prospectively enrolled 226 Japanese patients with CHC, and investigated the impact of hepatic steatosis and its related SNPs, including rs8099917 of IL28B, rs738409 of PNPLA3, and rs14158 of LDL receptor, on outcomes of peg-interferon and ribavirin therapy. In multivariate logistic regression analysis, significant factors affecting the severity of hepatic steatosis were high body mass index and the minor alleles of IL28B SNP (p＝0.020 and 0.039, respectively). The risk alleles of PNPLA3 SNP also showed weak association (p＝0.059). Severe steatosis and the minor alleles of IL28B SNP were significantly associated with null or partial virological response in patients with HCV genotype 1, as were female gender, and low LDL cholesterol (p＝0.049, and ＜0.001, respectively). The SNP genotype of PNPLA3 and LDL receptor did not have a significant impact on therapeutic outcomes. With respect to the SNP sites examined, the SNP of PNPLA3 has a weak association with severe hepatic steatosis, but not with the outcome of interferon therapy.