The possibility that alveolar macrophages and type-II cells can accumulate taurine was examined. The study involved measuring the taurine content of the cells, the rates of taurine uptake in the presence of a normal plasma concentration of taurine, the concentration dependence and kinetic parameters for the transport system, and the effects of metabolic inhibitors or ouabain on the transport processes. Lung cells were isolated from male Sprague- Dawley-rats. Taurine uptake displayed two components: the initial component was rapid and of short duration, less than 30 minutes, whereas the second component of uptake was less rapid and of longer duration, 30 to 120 minutes. The rates of taurine influx during both phases of uptake were greater for alveolar macrophages than for type-II cells, although alveolar type-II cells had a higher taurine content than alveolar macrophages. Alveolar macrophages displayed a higher proportion of leakage than type-II cells. Thus the higher taurine content of alveolar type-II cells may be due both to differences in the surface area of the cells and to differences in the ratio of carrier mediated taurine uptake to leakage of taurine from the cells.