The clinical spectrum of mixed cryoglobulinemia embraces several manifestations: recurrent vascular purpura, weakness, arthralgia/arthritis, glomerulonephritis, peripheral neuropathies, and Raynaud's phenomenon. Mixed cryoglobulinemia is currently treated with steroids, low-antigen content diet, immunosuppressors, plasma exchange, and antiviral therapy, namely, alpha -interferon alone or, more recently, in association with ribavirin. In the present research, we verified the effectiveness of combined therapy with interferon and ribavirin on asymptomatic mixed cryoglobulinemia in naïve (never treated before) patients with chronic hepatitis C. We enrolled 50 consecutive patients, 31 males and 19 females, with chronic hepatitis C who showed a sustained response to combined antiviral therapy (interferon and ribavirin). Before treatment, cryoglobulins were detected in 25 subjects (50%). Only 1 of the 25 patients with asymptomatic mixed cryoglobulinemia had persistence of cryoglobulins at the end of the follow-up period. Unexpectedly, in 7 of 25 subjects without mixed cryoglobulinemia before treatment, cryoglobulins became detectable after antiviral therapy. Our present study first reports the onset of asymptomatic mixed cryoglobulinemia in hepatitis C virus patients after clearance of the virus from blood obtained with a combined antiviral treatment. Possible explanations are discussed. Our data also suggest that the appearance of a clinically evident mixed cryoglobulinemia cannot be excluded in this kind of subject.