The authors describe the potential effects of ambroxol on the pulmonary disorders induced by antineoplastic agents (in particular, bleomycin and the nitrosureas). An experimental stage focussed attention on the early modifications occurring in the alveolar surfactant and in the afflux of inflammatory and immune-effector cells following bleomycin-induced lung fibrosis in the rat (by intratracheal instillation). The ambroxol-protected rats showed a slower drop of alveolar lecithins in the first few hours after bleomycin administration and a lower afflux of neutrophils, macrophages and lymphocytes. In the clinical stage, respiratory function was studied in two groups of cancer patients treated with nitrosureas or bleomycin. Preliminary findings indicate a rapid worsening of some functional parameters--maximal expiratory flow at 25% vital capacity, diffusing capacity for carbon monoxide and diffusing capacity/ventilation--in controls, while no such changes occurred in the ambroxol-protected subjects. The possible pathogenetic implications of these results and perspective for future investigations are discussed.