Levels of gastric juice nitrite, several urinary N-nitroso compounds, and other analytes were examined among nearly 600 residents in an area of Shandong, China, where precancerous gastric lesions are common and rates of stomach cancer are among the world's highest. Gastric juice nitrite levels were considerably higher among those with gastric juice pH values above 2.4 versus below 2.4. Nitrite was detected more often and at higher levels among persons with later stage gastric lesions, especially when gastric pH was high. Of those with intestinal metaplasia, 17.5% had detectable levels of gastric nitrite, while this analyte was detected in only 7.2% of those with less advanced lesions. Relative to those with undetectable nitrite, the odds of intestinal metaplasia increased from 1.5 (95% confidence interval = 0.6-4.1) to 4.1 (95% confidence interval = 1.8-9.3) among those with low and high nitrite concentrations, respectively. Urinary acetaldehyde and formaldehyde levels also tended to be higher among those with more advanced pathology, particularly dysplasia. However, urinary excretion levels of total N-nitroso compounds and several nitrosamino acids differed little among those with chronic atrophic gastritis and intestinal metaplasia and dysplasia, consistent with findings from recent studies in the United Kingdom, France, and Colombia. The data from this high-risk population suggest that elevated levels of gastric nitrite, especially in a high pH environment, are associated with advanced precancerous gastric lesions, although specific N-nitroso compounds were not implicated.