The aim of present investigation was to establish possible histochrome's effect on the renal excretory function. During 10 days was being administrated histochrome by subcutaneous injections in dose 10 mg/kg. Every 2 days was being detected daily renal excretions of water, creatinin, sodium and potassium. Long-term histochrome's administration was followed by a fivefold increasing of water excretion and comparable amplification of creatinin. Sodium's and potassium's excretions were increasing to a lesser degree. The revealed histochrome's diuretic effect qualitatively reminds action of diuretic plants, but quantitatively it was compared with thiazid's one.