The widespread use of alpha-interferon (IFN-α) therapy in different diseases draws attention to its side effects, such as autoimmune-related diseases, especially thyroid autoimmune dysfunctions. Data about hepatitis and nonhematologic neoplasia are available, while data about hematologic malignancies are fragmentary. We studied the incidence of autoimmune-related disturbances and thyroid dysfunctions in 54 consecutive patients suffering from hematologic malignancies, treated with recombinant human IFN-α for a mean time of 15.9 ± 8.9 months. Our results minimize the incidence of autoimmune dysfunctions in hematologic malignancies as side effects of IFN-α therapy. We registered the appearance of autoantibodies in only 3 females (5% of total): 2 patients (1 affected with essential thrombocythemia and one with multiple myeloma) presented antithyroglobulin antibodies with no clinical symptoms; 1 patient, affected with essential thrombocythemia, developed antinuclear antibodies with arthralgia and myalgia. ARA criteria for systemic lupus erythematosus were not fulfilled but the therapy had to be interrupted. No patient developed thyroid dysfunction. In patients with hematologic malignancies, the dosage and the duration of IFN-α treatment do not seem to influence the appearance of autoantibodies, while female sex appears to be a risk factor.