Risk assessment for occupational exposure to antiblastic chemotherapeutic drugs (ACD) is carried out by means of environmental and biological monitoring. These practices are not widespread and furthermore their results are frequently difficult to interpret. This paper discusses some of the most important aspects of risk assessment for ACD and in particular for their exposure evaluation. The following guidelines are proposed: a) working rooms, working procedures, type and quantity of drugs, and preventive measures must be checked using a standardized scheme for collecting data: an example of a check list experimented in some Italian hospitals is presented; b) cyclophosphamide, 5-fluorouracil, and Pt coordination compounds have been identified as tracers of drug mixtures usually administered, and their determination is recommended both in environmental and biological samples; c) for a correct evaluation of exposure, ACD should be determined firstly on the contaminated surfaces or on work clothes and secondly in urine of workers; the measurement of ACD in air must be limited to well documented conditions of high exposure and the urinary mutagenicity tests should be avoided; d) the biological monitoring practices should be enhanced, in particular the determination of ACD adducts to proteins and nucleic acids as promising indicators of effective dose.