The contamination with fluorouracil, cyclophosphamide and methotrexate was studied in a hospital pharmacy department where these drugs were prepared. In the preparation room, air samples were taken before and during preparation of the drugs. Methotrexate was detected in one sample which was collected during preparation (0.3 micrograms/m3). Spot samples were taken in the vertical laminar airflow safety hood before and after preparation of the drugs and after cleaning of the hood. Contamination of the laminar airflow hood was: cyclophosphamide: 1-160 ng/cm2; fluorouracil: 10-62 ng/cm2 and methotrexate: 2-633 ng/cm2. Spot samples from the floor in front of and beneath the laminar airflow hood showed contamination with especially fluorouracil (48-236 micrograms/m2). The gloves used during preparation of the drugs were contaminated mainly with fluorouracil (5-980 ng/cm2). Urine samples from two workers involved in the preparation of the drugs were analysed for unmetabolized cyclophosphamide; it was not detected. Although no uptake of cyclophosphamide was established, it is shown that the methods for measurement of cyclophosphamide, fluorouracil and methotrexate in the preparation room are applicable for the control of occupational exposure to these drugs.