The authors suggest a method for the detection of 'medium molecules' to be used for rapid diagnosis of poisoning. They present their arguments in favor of a higher specificity of this method as against other rapid methods for 'medium molecule' detection in biologic fluids of the body. The authors' data evidence a high correlation between the results of the suggested method and gel filtration technique. The procedure may be used for the rapid diagnosis of peptidemia severity in the patients with grave endogenic intoxication and in cases when endotoxicosis is not the underlying condition.