An inter-individual variability in sensitivity to mutagen-induced genotoxicity was studied in respect to an estimation of larynx cancer risk. Bleomycin induced chromosome breaks were analysed in blood lymphocytes proliferating in vitro in a group of 35 larynx cancer subjects and in 18 healthy controls. A significantly higher index of chromosome breaks was found in larynx cancer subjects as compared with the controls. The distribution of individual results indicates that subjects oversensitive to bleomycine were identified only among laryngeal tumour patients. A potential usage of bleomycin test in tumour prognosis is discussed.