Twelve patients of both sexes (5 women, 7 men; mean age = 39,9) suffering from marked anxiety as defined by DSM III for generalised anxiety (score greater than 20 on the Hamilton-A scale) but in good physical health, were given 15 mg of clorazepate daily at 8 p.m. for a period of 28 days. Desmethyldiazepam, the active metabolite of clorazepate was measured in blood samples on day 1, 14 and 28 of the experiment as well as the level of anxiety on the Hamilton scale. Anxiety decreased significantly between day 1 and day 14 (mean score declining from 33,9 to 18,4) and from day 14 to day 28 (mean score 18,4 to 14,7). Desmethyldiazepam reached its maximum blood concentration 2 hours after the first intake of clorazepate. A plateau had been reached at day 14 and remained stable up until day 28, indicating the absence of cumulating effects. The dosage remained the same for all patients during the 28 days of the experiment. There were no drop outs and no undesirable effects.