The major features of levamisole immunotherapy are distilled from experiences gained so far. The biochemical effects of levamisole are discussed in view of its effects on T lymphocytes and phagocytes. Potential indications for levamisole treatment are classified after Jerry et al. as immune deficiencies or as immune dysregulation syndromes (such as rheumatoid arthritis and cancer). After a scrutiny of investigations in cancer patients, the conclusion emerges that, in a subsection of patients, mainly those with poor prospects, levamisole improves the prognosis after effective chemotherapy, radiotherapy or surgery when given in time and in an appropriate dosage.