Waist circumference (WC) is a useful measure for identifying children at higher risk of complications related with abdominal fat. We determined the magnitude of central adiposity, single and combined with overweight and obesity in infants 1-5 years old. We also identified smoothed age-and sex-specific WC percentile values, which were compared with other countries available data. This was a cross-sectional study in children of 8 day care centers located in Monterrey, Mexico (n = 903, 431 boys and 472 girls). Because the risk due to abdominal obesity begins at WC percentile > or = 75, we considered two thresholds, percentile 75 y 90. Overweight was defined based on body mass index at percentile 85-94 for age and sex; and obesity, at percentile > or = 95. Analysis consisted of point prevalence and 95% confidence intervals. The LMS Chart Maker Light software was used for smoothing WC percentile values. The study population mean age was 2.7 +/- 1.0 years. Mexican children's WC was 1 cm above that of Afro-American; and it was up to 4 cm below that Mexican-American. Prevalence of central obesity with WC at percentile 75 combined with overweight/obesity was 25.1% (95% CI 22.3-28.0) and single, 15.4% (95 CI% 13.0-17.8). Prevalence of single abdominal obesity with WC at percentile > or = 90 was 4.4% (IC 95% 3.0, 5.8). Day care centers represent a key opportunity for defying central obesity. WC can be used since early age for screening and caring children at higher cardiovascular risk.