Bile salts are known to injure the gastric mucosa and may be involved in the pathogenesis of gastric stress ulceration, a feared sequela of shock. Although the induction of bile injury to the stomach has been extensively studied, recovery from such an injury has not. In the studies reported here the period after removal of bile was examined to see whether the mucosa could return to pre-bile-exposure status under various circumstances. Recovery from a bile salt-induced injury was studied in three mongrel dogs with Heidenhain pouches. Net acid back diffusion (NABD) was measured with a recirculating system incorporating a pH stat and was measured with a recirculating system incorporating a pH stat and autoburette, and transmucosal electrical potential difference (PD) was measured by usual methods. The effects of exposure to 5 mM taurodeoxycholate at pH 2 for 30 minutes were studied. This exposure increased net acid back diffusion from 23 +/- 5 to 184 +/- 16 micro Eq/10 min (P less than 0.01) and reduced PD from 56 +/- 2 to 18 +/- 2 mV (P less than 0.01). After injury the pouches were copiously irrigated with saline to remove bile, and then recovery was observed as the pouches were perfused with pH 1, 2, or 7 HCl solution made isotonic with NaCl. The recovery values were compared with the same dog's preinjury values at the same pH perfusion. The data showed that at pH 2 and pH 7, PD and NABD returned to preinjury levels within 90 minutes after bile injury. At pH 1, however, recovery did not occur. The pH dependence of recovery from bile-induced injury may have relevance to patients with episodic reflux of bile into the stomach.