With the advent of biotechnological advances and knowledge of molecular and cellular biology, radioimmunotherapy (RIT) has become a highly promising oncologic therapeutic modality with established clinically efficacy, particularly in non-Hodgkin's lymphomas. This paper provides a short survey of the basic science of RIT and the various monoclonal antibodies and radionuclides used. A brief review of the published literature on the clinical applications of radioimmunotherapy, particularly in non-Hodgkin's lymphoma, is provided. New research data indicate many potential areas of development of this modality, including haematological and solid-organ radioimmunotherapy as well as new radionuclidic approaches and clinical protocols.