The aim was to study pulmonary function after Hodgkin disease or non-Hodgkin lymphoma in childhood and to evaluate if younger age at diagnosis and therapy is a risk factor for reduced pulmonary function. We studied a population-based sample of survivors of Hodgkin disease (n = 22) or non-Hodgkin lymphoma (n = 19) in childhood. Pulmonary function test results were compared with reference values for our laboratory, generated by adjusting published reference values to fit 348 healthy never-smokers from a local population study. Data were analysed as standardised residuals, which are [observed minus predicted value] divided by the residual standard deviation of the reference equations. At a median of 11 years after diagnosis (range 2 to 24), the participants had significantly reduced lung volumes and transfer factor, unrelated to the few pulmonary symptoms. On average, the total lung capacity was reduced to -0.9 standardised residual and the transfer factor was reduced to -1.3 standardised residual. Young age at therapy seemed to be a risk factor for reduced lung function, especially when treatment included thoracic irradiation. No significant toxic synergism was observed between smoking and previous cancer therapy. Therapy without thoracic irradiation but with doxorubicin and cyclophosphamide was almost as toxic to lung function as therapy with thoracic irradiation but without doxorubicin and cyclophosphamide. This suggests a pulmonary toxicity of doxorubicin or cyclophosphamide. In conclusion, lung volumes and transfer factor were reduced several years after childhood Hodgkin disease or non-Hodgkin lymphoma, with young age at therapy as a risk factor, especially when combined with thoracic irradiation.