In the majority of patients with acute hepatitis C the anti-HCV IgM antibodies in serum were present, however, some patients with chronic hepatitis C were positive for anti-HCV IgM too. The aim of this study was to assess the presence of anti-c22 IgM in patients with chronic hepatitis C and to determine whether the positivity for anti-c22 IgM has an impact on the histological finding in the liver. A total of 88 patients were examined (44 women, 44 men), mean age 48 years. The first group comprised 24 patients positive for both anti-HCV IgG and anti-c22 IgM, the second group 38 patients positive for anti-HCV IgG only, and the third group 26 patients negative for both anti-HCV IgG and anti-c22 IgM. Of 62 anti-HCV-IgG-positive subjects 24 (39%) were positive also for anti-c22 IgM. Of 24 patients who received a blood transfusion 9 (37.5%) were positive for anti-c22 IgM. The mean serum alanine aminotransferase (ALT) activity was significantly higher in subjects with anti-c22 IgM than that in subjects without them (p = 0.006), however, the difference in aspartate aminotransferase (AST) was not significant (p = 0.09). Histological examination was performed in 46 patients. Two-thirds of the patients with anti-c22 IgM had either cirrhosis or chronic active hepatitis (CAH) while only one third of the anti-HCV-positive patients without anti-c22 IgM had CAH or cirrhosis. The results showed that approximately 40% of the patients with CAH and cirrhosis had anti-c22 IgM, a significantly higher serum ALT activity and more serious histological finding in the liver than anti-HCV-positive patients without anti-c22 IgM.