To determine whether an association exists between abnormal pulmonary function tests (PFT) before bone marrow transplantation (BMT) and the rate of pulmonary complications after BMT, we retrospectively reviewed all transplants performed in our center between March 1984 and December 1990. A total of 163 patients, 15 years of age and older, with a hematologic malignancy or a solid tumor were treated with intensive therapy and autologous (118) or allogeneic (55) BMT. Sixty patients (37%) developed a pulmonary complication which contributed to patient death in 29 transplants (18%). Patients with pulmonary metastases, prior thoracotomy, or prior radiation to the chest had a higher frequency of abnormal PFT. By univariate analysis, patients with abnormal FVC, FEV1, or TLC before BMT had a significantly increased rate of pulmonary complications (p < 0.005). By multivariate analysis, the rate of pulmonary complications was significantly associated (p = 0.004) with abnormal FEV1 only: in the first 2 months after transplantation the rate was 65% in patients with FEV1 < 70% in contrast to 34% in patients with FEV1 > or = 70% (risk ratio = 1.9). There was no association, however, between abnormal pretransplant PFT and fatal pulmonary complications. We conclude that patients with pretransplant ventilatory defects have a higher risk of pulmonary complications after BMT, but the incidence of fatal complications was not significantly increased, although we cannot exclude a diminished study power due to the sample size. We believe that patients with abnormal PFT should not be excluded from transplantation if the anticipated anti-tumor effect is estimated to be substantial, but additional preventive measures may be necessary.