1. The relationship between urine pH, modified by the oral administration of either ammonium chloride or sodium bicarbonate, and the urinary excretion of prostaglandin E (PGE) was studied in healthy female subjects.
2. The urinary concentration of PGE, normally constant in man, was significantly higher (P<0.02) in alkaline than in acid urine. pH-dependent metabolism and flow-dependent excretion were identified as two factors liable to obscure the demonstration of the pH-dependency of the urinary excretion rate of PGE in man.