This study was conducted to evaluate gastric acid secretion in acute renal failure, highlighting the roles of renal mass and gastrin hormone. Acute uremic rats were divided into bilateral nephrectomized and bilateral ureteric obstruction groups. Gastric juice was collected for 2 h and analyzed for volume, free acidity, total acidity, and total acid output. Plasma levels of creatinine, urea, and gastrin were also determined. Bilateral nephrectomized and bilateral ureteric obstruction groups showed a significant increase in levels of free acidity, total acidity, and plasma gastrin. Compared with the ureteric obstruction group, nephrectomized rats showed a significant increase in gastric juice volume, total acid output, and plasma gastrin levels. Following pentagastrin stimulation, gastric juice volume, total acid output, free acidity, and total acidity were increased in the bilateral nephrectomy and ureteric obstruction groups compared with the respective control groups. The free and total acidity and total acid output also increased compared with the respective non-stimulated groups. Plasma creatinine and urea levels were significantly positively correlated with plasma gastrin, free acidity, and total acidity. Creatinine was positively correlated with total acid output, and gastrin was positively correlated with total acidity. In conclusion, acute renal failure promotes gastric acid hypersecretion that could potentially be attributed to high levels of gastrin hormone and uremic state per se.