Sixty-five patients with hematological malignancies (25 multiple myeloma, 18 Hodgkin's disease, 22 non-Hodgkin's lymphomas) who received a carmustine-based regimen followed by autologous PBPC transplantation, were studied retrospectively to evaluate the incidence of post-transplant non-infective pulmonary complications (NIPCs), risk factors predictive of NIPCs, and response to steroids. Carmustine (BCNU) given i.v. at a dose of 600 mg/m2 was combined with etoposide and cyclophosphamide in 40 patients (BCV regimen) and with etoposide and melphalan in 25 patients (BEM regimen). Seventeen of 65 patients (26%) had one episode of NIPCs. The median time to NIPCs was 90 days (52-289). Factors that increased the risk of developing NIPCs on multivariate analysis were female sex (P < 0. 001) and BCV regimen (P < 0.05). All patients with NIPCs received prednisone at a dose of 1 mg/kg body weight for 10 days then tapered by 5 mg every two days; complete response to steroids was achieved in 15 of 17 patients; one unresponsive patient died of interstitial pneumonia. BCNU given at the dose of 600 mg/m2 is well tolerated when associated with melphalan and etoposide. In females and in patients receiving BCNU with cyclophosphamide, a BCNU dose reduction may be advisable. Bone Marrow Transplantation (2000) 25, 309-313.