1. The urine of the male adult mongrel dogs was collected through the urethral catheterization at every 30 minutes for 1 hour before cancer extract was injected into the leg vein. Collection of the urine was continued for about 3 to 4 hours after injection. Uropepsin was measured by modified West's method. 2. There was no change on the quantity of uropepsin in the series without any injection, compared to slight increase in other series which were injected with physiological saline solution. Intravenous injection of the muscle extract of the stomach wall made a moderate increase of the uropepsin in urine. The injection of the cancer extract made a more remarked increase of uropepsin than the control. 3. The gastric juice of the adult male dogs from the Wedge or Heidenhain's pouch was collected at every 20 minutes and its quantity and peptic activity were measured. At the same time the urine was collected through the urethral catheterization at every 30 minutes and studied on uropepsin. As a result of intravenous injection of the cancer extract, the gastric pouch secretion decreased moderately and its peptic activity was depressed, however the uropepsin level in the urine increased. In most instances, when the peptic activity was most depressed, the uropepsin level in urine reached the peak, except one case on which the peptic activity showed the parallel relation with the uropepsin level in urine. 4. From the above experiments, it appeared that the gastric pepsin of the pouch secretion was not in parallel relation with the uropepsin in urine, and it was supposed that the endocrine mechanism of pepsinogen may counteract the exocrine mechanism of pepsinogen.