SummaryThe author exposes the most recent experiments in the field of cancer chemotherapy with alkylating agents. He proposes a classification of these substances, using the chemical structure of the prosthetic group as a base for this classification. Recent works have tried to increase the activity of chemo-thcrapcutic agents by synthesizing complexes with a prosthetic group acting, by its chemical structure, as a carrier for the alkyl groups. The purpose is to find a carrier which preferentially it«leads»the active group within the cancer cells. The pioneer work in this field seems to be the synthesis of substances with an aminoacid as a carrier (Salcolysine). In more recent agents, the active group is linked to a pyrimidin, a dipeptide or a polypeptide. In the«dual»antagonists, the same molecule contains the alkyl group and another active substance, for instance urcthane. Cyclophosphamide is inactive in its complex form and would be activated by an enzyme which is particularly abundant in the cancer cells.In the last part the author gives some aspects of the new methods of administration of the alkylating agents, such as arterial catheterization, extracorporeal circulation, chemoprophylaxy and associations with other therapeutic measures.