The article by Shapiro et al1 wherein a nomogram relating daily theophylline dose requirements to single serum levels appears to us either misleading or in error. According to our calculations, the upper and lower limits depending on K = 0.07 to 0.5 hr-1 would give a value with no units: dose (mg/kg/day) = K x V x 24 hr x 10 µg/ml = 0.07 liter/hr x 0.45 liter/kg x 24 hr x 10 µg/ml = 0.07 liter/hr x 450 ml/1,000,000 µg x 24 hr x 10 µg/ml = 0.00756 = 0.5 liter/hr x 450 ml/1,000,000 µg x 24 hr x 10 µg/ml = 0.054.