Background: Patients with chronic viral hepatitis are at high risk of developing hepatocellular carcinoma (HCC). Various predisposing factors have been described for the occurrence of HCC in these patients. The aim of the present study was to identify these risk factors. Method and Material: A retrospective descriptive epidemiological study, of 549 patients with chronic viral hepatitis was conducted. Patients were examined from January 1st 2007 to September 31st 2013 at the Hepatology outpatient unit of a General Hospital of Athens-Greece. Demographic, clinical characteristics of patients and laboratory test results were gathered from the registry of the outpatient unit. Statistical analysis was performed with the PASW18 software, using Pearson’s chisquare test. P values of less than 0.05 were considered significant. Results: Files of 549 examined patients in the outpatient unit were reviewed and 253 (46.1%) were diagnosed with chronic hepatitis B (CHB) and 296 (53.9%) with chronic hepatitis C (CHC). The majority of patients (57.2%) were men and less than 65 years old (87.4%). The frequency of HCC was 4.4% (24 patients). Fifteen patients were diagnosed with CHB and 9 with CHC (P=0.039). The factors found to be associated with the development of HCC in our study were age ≥ 65 years (P<0.001), diabetes mellitus (P=0.003), chronicity (≥ 10 years) of viral infection (P=0.007) and liver cirrhosis (P<0.001). Conclusions: The prevalence of HCC was significantly higher in patients with CHB compared with CHC patients. Age ≥ 65 years, diabetes mellitus, chronicity of viral infection and liver cirrhosis were the main predisposing factors for the occurrence of HCC. The early diagnosis of diabetes and the early treatment of viral hepatitis could contribute to the prevention of HCC.