Rats were subjected to inhalation, intratracheal, skin-irritating, intrastomach or i.p. effects of the following compounds: ZP 7, Zp 10M, ZP 24, ZG 2, and ZG 4M and their solvent isoamylphthalimide. Various pyrazole (I) and hydroxynaphthoic acid derivatives, via different routes and various exposure durations, produced analogous effects: a decrease in the saturation of blood with O, metabolism formation increase in the serum arginase and hypochloruria. The solvent isoamylphthalimide, in addition increased bilirubin level in the urine. I and hydroxynaphthoic acid derivatives had low toxicity; ZP 7 was the most toxic.