The cyclic adenosine monophosphate (AMP-c) excreted in the urine over a 24 hour period was systematically measured in 40 patients suffering from alcohol withdrawal syndrome (AWS) in varying degrees from slight to delirium tremens. In almost all patients the level of excreted AMP-c was high bul returned to normal when the clinical picture together with arterial pressure and cardiac frequency, was normalised. This shows the primary importance of the central sympathetic-adrenergic system in the pathogenesis of AWS and the value of monitoring urinary AMP-c excretion during the syndrome.