Interferons are naturally occurring substances. In fact, interferons are intercellular signalling proteins produced by cells in response to various biological and synthetic stimuli. Three major classes of interferons have been identified: interferons alpha, beta and gamma. Interferons originate from natural sources and are products of recombinant technology. Two forms of recombinant alpha-interferons, 2a and 2b, are available. Alpha-interferons are secreted and synthetised by leucocytes and lymphoblasts. The objective herein is to review the current therapeutic implications of alpha-interferons. Interferons alpha have antiviral, anticancer and immunomodulatory activities. Clinical trials have proved interferons alpha to be of special value as adjuvant therapy (first line drugs) for hairy cell leukemia, virus hepatitis B and C and condylomata acuminata. The efficacy of interferons alpha is now also being evaluated in other malignancies and virus diseases. For instance, interferons alpha are an important advanced modality in the management of chronic myelogenous leukemia and can be considered a first-line therapy option in patients who cannot receive or relapse following allogenic bone marrow transplant. Of course, further research is also required to evaluate combination therapies with interferons alpha and other agents. Presently malignancies have the broadest potential in application of interferons alpha therapy. Hairy cell leukemia responds to interferons alpha in up to 90% of patients, Kaposi\'s sarcoma, which occurs primarily in association with AIDS, benefit in up to 40% of patents, lymphomas respond in about 65% of patients whereas chronic myelogeneous leukemia in more than 80% of patients in early cases. The uses of interferons alpha in infectious diseases (condylomaty acuminata, rhinovirus infection, protozoal, parasitic and fungal intracellular infections) may also be significant. However, the cost of interferons alpha is too high. This makes interferons alpha a second line therapy, but not in patients where it is more effective than alternative treatment. Interferons alpha are cytokines (intercellular signalling proteins) which have antiviral, anticancer and immunomodulatory activities. Interferons alpha therapy represents an important advanced modality in the management of patients with hematological diseases, malignancies, lymphomas, solid malignant tumours and viral infections. Clinical trials have proved interferons alpha to be of special value as first line drugs for hairy cell leukemia, virus hepatitis B and C and condylomata accuminata. Interferons alpha are used as single primary therapy, adjuvant therapy and maintenance therapy. The limiting factor for the application of interferons alpha is the cost of treatment.