Objetives. Evaluate occupational exposure to cyclophosphamide in nine hospitals of Peru. Materials and methods. Crosscutting observational study conducted in 2010, for which 24-hour urine samples were obtained from 96 employees of the oncologic mixture units and oncology services of nine hospitals in Peru, the quantification of cyclophosphamide was done through the GC-MS methodology (Gas Cromathography-Mass Spectroscopy). Additionally, working surfaces were tested by obtaining samples with wet wipes for identification of cyclophosphamide. Results. Cyclophosphamide was detected in urine samples in 67 employees (average concentration of excretion: 74.2 ng/24 h), accounting for 70% of the total population to be assessed. Based on the excretion, total exposure among hospitals can be classified as high level (>18.9 ng/24 h), moderate level (1,725 - 18.9 ng/24 h) and low level (<1,725 ng/24 h), with a percent incidence of 31.3; 26.0 and 42.7% respectively. Additionally, as part of the environmental evaluation, concentrations of cyclosphamide were found in 14.72, 14.98 and 5,12 ng/cm2. Conclusions. Contamination through cyclophosphamide in areas where oncological preparations are done and the presence of cyclophosphamide in urine samples of workers exposed to cytostatics substance were observed.