Earlobe capillary pH and blood gases in asthmatic children were compared to arterial values. Hyperemia of the earlobe was produced by applying thurfyl nicotinate (Trafuril). Approximately 15 min later capillary blood was obtained simultaneously with a radial arterial sample. Earlobe capillary PO2, PCO2, and pH correlated well with arterial values. This technique, is simple, safe, and appears to be a satisfactory substitute for arterial blood in normotensive asthmatic children. © 1975.