The aim of this work was to evaluate the nutritional condition of the children in age of preschool in San Luis Potosí, Mexico, and its relation with the perception of the mother respect to their nutritional state, this through of an opinion poll. The result showed an age average of 55.9±3.54 months for the girls and 56.5±3.54 for the boys. For this age the girls showed a BMI average of 14.66±0.83 between the percentiles 5th and 50th with the middle in the percentile 25th which is 14.77. Meanwhile the boys showed a BMI of the 15.53±1.87 just in the middle of the percentile 50th (15.48). This result showed that the boys seem to have better feeding that the girls, maybe promote for cultural and social issues. This was corroborated with the results obtained with the perception of the mother. Meanwhile the values of IBM in the boys had normal levels or higher, the mother had the perception that the boy had weight low. However different situations happen with the girls, the mothers identify the weight low in the girl but with similar values to the boys, even though the girls have reality lower values of IBM that the normal middle, nevertheless the levels of caloric consume seems to be normal.