Recent experimental and clinical reports have demonstrated that beta-adrenergic blockade impairs and beta-adrenergic stimulation enhances in vivo extrarenal potassium uptake in man. In some allergic patients extrarenal potassium disposal in vivo was reduced compared with normal subjects. In the present study we report that in vitro salbutamol induced potassium uptake by red blood cells may be reduced in some atopic patients. By using a ligand binding assay on cultured human A431 cells, we tried to determine whether in the sera of these atopic subjects there could be anti beta-adrenergic receptor autoantibodies. The results suggest that the observed reduced response to salbutamol of atopics' red blood cells does not depend on autoantibody activity.