To investigate the safety of repeated bronchoalveolar lavage (BAL) and the variability of commonly measured parameters from BAL to BAL in the same subject, we performed a total of 59 BALs in 16 normal volunteer subjects. The BAL was performed with 120 ml (three aliquots of 40 ml) of room temperature, normal saline in a lingular subsegment. Four subjects had five BAL, three had four BAL, and nine had three BAL performed at minimal intervals of six weeks. The BAL analysis included percentage of lavageate returned, cell number, and percentage of alveolar macrophages, lymphocytes, neutrophils and eosinophils. Relatively similar percentages of lavageate were returned on each lavage. There was considerable variability in the cell numbers obtained both within and between subjects, although some subjects had consistently high, low, or normal cell numbers returned from each lavage. Cell differential was the most consistent parameter on repeated BAL analyses, but isolated "abnormal" elevations in the percentage of one or another cell type were occasionally noted. These were unrelated to either the number or relative sequence of the BALs. Pulmonary function tests performed both before and after the repeated BAL showed no significant change and participants noted no subjective deterioration in pulmonary function. This study supports the safety of repeated BALs in the normal subject, but the variability in cell numbers obtained and isolated, "abnormal" elevations of inflammatory cells occasionally noted in this normal population indicate that BAL parameters in patients need to be interpreted with extreme caution.