Experiments on young rats have shown that diplacin and d-tubocurarine in doses amounting to 1/15-1/20 of LD50 lower the ability of hydrocortisone to interfere with the physical development of the animals. Metamisyl, metacin, gangleron and benzohexonium have no such properties. In adult rats and guinea-pigs, diplacin exerts no effect on the intensity of anti-inflammatory and antiallergic action of the hormonal drug, while d-tubocurarine diminishes the anti-inflammatory effect of the corticosteroid in experimental formalin-induced paw edema and weakens its effect on the immediate type hypersensitivity.