We analyzed the concentration of plasma epinephrine, norepinephrine, dopamine and C-AMP and urinary cortisol, histamine and creatinine in 28 children over a period from 4 p.m. to 8 a.m. 15 children were suffering from nocturnal asthma, 13 had no asthma problems. The cortisol-levels of both, the asthmatic and the healthy children were almost identical, the minimum cortisol-concentrations were found at 8 p.m. The concentration of plasma epinephrine in the asthmatic children was significantly higher than in the control group. Both groups showed minimum levels at 12 p.m. Plasma norepinephrine showed a continuous course with a raise in the early morning hours in both groups. Children without asthma had a continuous decrease of norepinephrine during the sleeping period and an increase in the early morning. Dopamine was significantly lower in the asthmatics. C-AMP was also on a lower level, but the difference between both groups was not significant. Histamine showed an extreme variability in the asthmatic children and was on higher levels during the whole period compared to the control group. The raised epinephrine levels in children with nocturnal asthma could be understood as compensation to a dysfunction of the receptor-transducer-adenylcyclase-complex of beta 2-receptors. A reduction of beta 2-receptors by anti-asthmatic therapy could also be responsible for these epinephrine levels. The significant difference in dopamine levels between children with and without nocturnal asthma is poorly understood. The increase of epinephrine and the decrease of dopamine could be caused by a modulated synthesis of catecholamines in children suffering from nocturnal asthma.