Prostanoid excretion with urine in children suffering from glomerulonephritis indicates that in the kidneys the output of prostacycline decreases and that of thromboxan rises. In glomerulonephritis children prostacycline and prostaglandin E promote the maintenance of glomerular filtration, which is evidenced by the reduction of their output in the stage of chronic renal failure. The growth of renin and antidiuretic hormone synthesis in children suffering from nephrotic glomerulonephritis is not accompanied by the increase of the output of prostaglandin E, their renal antagonist, and may be one of the reasons of the development of the edematous syndrome.