We have prospectively studied patients with type II cryoglobulinemia since 1985 to assess the efficacy of treatment with interferon-alpha at cumulative doses ranging from 234 to 849 MU. In the present study we retrospectively evaluated in this cohort parameters associated with complete response to therapy in 31 consecutive patients with type II cryoglobulinemia associated with hepatitis C virus (HCV) infection. Prevalence of complete response of cryoglobulinemia (disappearance of symptoms and signs of vasculitis and decrease of cryocrit below 10% of the initial value) was 62%, with a median response duration of 33 months and a range of 3 to 100 months. Three patients were putatively cured, as they remained in complete remission for more than 5 years off therapy. Eighteen patients (58%) had liver disease evidenced by histopathology and/or raised transaminase levels. Prevalence of normalization of transaminase levels was 100%, with a median response duration of 36 months. Relapse of hypertransaminasemia occurred in 100% and 8% of patients receiving less than or greater than 621 MU, respectively. By logistic regression analysis, the only pretherapy parameter that associated significantly (P = .0393) with complete response of cryoglobulinemia was the solitary anti-C22 (HCV core) antibody pattern, which was observed in 29% of patients. Association with older age and low cryocrit approached statistical significance (P = . 06), while no significant correlations were found with serum IgM levels, duration of disease, HCV genotype, NS5a gene mutations, liver histology, HLA-DR phenotype, or WA cross-idiotype. Complete responses were also associated, on univariate statistical analysis, with low pretherapy HCV viremia. Responses were accompanied by decrease of viremia, of anti-HCV antibody levels and cryocrit. The usefulness of a high dose regimen is underscored by the higher rates of sustained responses of cryoglobulinemia and transaminase levels compared with previous studies.