Mosaic pattern of gastric mucosa has been reported to be a sensitive and specific criterion for the diagnosis of portal hypertension and an important marker of nonvariceal upper gastrointestinal bleeding. So that the validity of this endoscopic sign could be assessed, 136 patients with portal hypertension, 25 chronic alcoholics without portal hypertension, and 366 controls were carefully endoscoped. Mosaic pattern was significantly (p less than 0.01) more common in portal hypertension patients (7.4%) than in controls (1.4%). It was not seen in chronic alcoholics. The incidence of mosaic pattern was 10.9% in cirrhotics, 2.9% in noncirrhotic portal fibrosis, and 5.4% in extrahepatic portal obstruction patients; the differences were not significant. Mosaic pattern was significantly (p less than 0.01) more often seen in postsclerotherapy (13.8%) than in presclerotherapy patients (2.6%). Bleeding from nonvariceal causes was uncommon, and was seen in only one patient (0.8%) showing mosaic pattern. Endoscopic gastric biopsies from areas showing mosaic pattern did not reveal any vascular abnormalities. In conclusion, gastric mucosal lesions are not very common in Indian patients with portal hypertension. In our experience, "mosaic pattern" is not a useful diagnostic feature in portal hypertension patients.