We studied the effect of physician specialization and board certification on costs and outcome of health care for a group of 213 patients with chronic lung disease followed prospectively for a year. Linear, semilogarithmic, and logistic regressions were used to control for differences in pulmonary function, functional ability, and sociodemographic characteristics. The cost of health services during the year was estimated from the total charges incurred. Patients' pulmonary function, functional ability, number of medical conditions, and insurance status were significant predictors of total cost. Combinations of these variables were important determinants of institutional days, outcome health status, and survival. Physician specialization and board certification were not significant descriptors of total costs or outcomes, although large variances limited the power of these findings. We conclude that differences in characteristics of primary care physicians do not appear to affect significantly the total cost or outcome of care for patients with moderate to severe chronic lung disease.