The aim of this study was to assess serum zinc levels in a cohort of healthy subjects and cirrhotic patients from Mexico City. A total of 153 healthy subjects and 100 cirrhotic patients, males and females aged 18-65, were studied. Inclusion criteria for healthy subjects were (1) Mexican-born with first and second generation relatives born in Mexico, and (2) somatometric (body mass index under 30) and clinical evaluation establishing that they had no underlying disease. Entry criteria for cirrhotic patients were (1) clinical and histological proven cirrhosis, (2) compensated liver disease (absence of coma, bleeding hemorrhage or refractory ascitis), and (3) cirrhosis of any cause. Zinc serum levels were measured with atomic absorption spectrophotometry. In healthy subjects, mean serum levels were 77.4 +/- 4.2 micrograms/dl (range 42.9-105.2 micrograms/dl). In cirrhotic patients zinc serum levels (58.9 +/- 16.1 micrograms/dl, range 22-88 micrograms/dl) were significantly lower than in healthy subjects (p < 0.05). A stepwise decline in serum zinc with worsening Child class (A, 73.4 +/- 13; B, 64.4 +/- 12; C, 55.8 +/- 15.6; p < 0.05 by ANOVA test) was found. In conclusion, this study confirms that zinc serum levels are significantly lower in cirrhotic patients and shows that zinc serum levels in a cohort of 153 healthy subjects from Mexico City were unexpectedly lower compared to those found in other countries. This last finding might be explained by different dietetic patterns and deserves further investigation.