To protect the organism against histamine liberated during anesthesia specific premedication is used including:--hydroxyzine (Atarax) which blocks the H1 histamine receptors, and is an anxiolytic,--tritoqualine (Hypostamine) which inhibits histamine synthesis,--epsilon aminocaproic acid (Hemocaprol) which prevents the antigen-antibody reaction and blocks the alternate route of complement. Twenty five patients were thus premedicated, 25 others received no premedication. All were put to sleep with Alfatesine. The results were judged on the clinical symptoms and the variations of histamine in whole blood. This premedication seems very efficacious, in particular in subjects with a high risk of histamine liberation.