Bronchoalveolar lavage is used to evaluate parenchymal inflammation in patients with diffuse lung disease. Normal values for lavage cell counts and proteins are derived primarily from young subjects who are free from lung disease; however, older patients who undergo bronchoalveolar lavage often have used cigarettes for long periods of time and have developed variable degrees of chronic bronchitis and/or chronic air-flow obstruction. Therefore, we evaluated the effects of cigarette use, chronic bronchitis, and chronic air-flow obstruction on lavage cell populations by performing bronchoalveolar lavage in 48 male patients who were undergoing diagnostic fiberoptic bronchoscopy. Sixteen patients (33%) had elevated percentages of neutrophils (greater than or equal to 10%) in lavage fluid. Fourteen of these (87.5%) had chronic cough and/or phlegm production, but only 9 (64.3%) met criteria for definite chronic bronchitis. Patients with moderate or severe air-flow obstruction, defined spirometrically, had significantly greater percentages of lavage neutrophils and lower percentages of macrophages than did patients with mild or no air-flow obstruction. The first lavage aliquot contained the greatest proportion of neutrophils and the smallest proportion of macrophages. The percentage of neutrophils declined and the percentage of macrophages increased in sequential aliquots. The data indicate that patients with chronic cough and/or phlegm production and chronic air-flow obstruction may have increased proportions of neutrophils in bronchoalveolar lavage fluid in the absence of diffuse parenchymal lung disease or infections. These variables must be taken into account when interpreting lavage cellular analyses.(ABSTRACT TRUNCATED AT 250 WORDS)