Lung function tests, including spirometry, and pulmonary transfer factor for carbon monoxide (TLCO), serum angiotensin-converting enzyme (sACE), serum copper (sCU++) and serum procollagen III peptide (sPIIIP) were measured in 20 patients with metastatic testicular carcinoma, before and after treatment with cisplatin, bleomycin, vinblastine or etoposide. A significant decrease of TLCO, total lung capacity and vital capacity was observed at the end of the treatment. No recovery of pulmonary function had taken place 2 yrs after the last dose of bleomycin. This result suggests that bleomycin-induced lung damage is not completely reversible. Serum angiotensin-converting enzyme, remained unmodified, whilst sPIIIP was found to be significantly increased at the end of chemotherapy, but normal 2 yrs after the completion of chemotherapy. Serum Cu++ showed a tendency to decline. No significant correlation was found between sACE, sCu++ and sPIIIP and lung function tests in the follow-up period. These results question the possibility that these markers could be useful indicators of bleomycin-induced lung damage.