Gastric mucosal blood flow (GMBF) was studied before and after highly selective vagotomy (HSV) by the pertechnate clearance technique. The studies were done on 24 mongrel dogs (Group A) under general anesthesia. Betazole was used to increase GMBF and gastric secretion (GS), and phenolred solution was used to correct the volume of GS collected by continuous aspiration. In all animals the measurements were done under resting, betazole-stimulated conditions, and then immediately after HSV. In 12 of the 24 dogs (Group B) the same measurements were done again 2 months later. The findings of the study indicate that betazole-stimulated GMBF was significantly decreased immediately after HSV (p < 0.001). Betazole stimulation resulted in a 6-fold increase of GMBF from the resting state before HSV, but only a 2-fold increase 2 months after HSV. GS showed a significant decrease right after HSV without a significant difference (p < 0.30) from the resting state. Two months postoperatively GS showed no significant difference from the resting state after betazole stimulation. There was a linear correlation between GMBF and GS before and after HSV but the correlation coefficients were not statistically significant.