The objective of this survey was to establish chronological patterns of eruption of permanent teeth in school children of the Los Reyes la Paz municipality in the State of Mexico. We examined 484 children -242 males and 242 females-between ages 5 and 15, who were attending government schools. A random stratified sample by age and sex was used for the survey. The dental examinations were carried out utilizing oral mirrors and daylight. The data collected was: age, sex, school name, group, school grade, date and permanent teeth already erupted at the moment of the examination. The mean age and range of permanent teeth erupted were determined and the results were presented in tables by sex and age. Results of permanent dental eruption were compared between sexes and they showed statistically significant differences (P less than 0.05), in 86 percent of the examined teeth. Earlier eruption was found more frequently in females than in males. We observed that lower teeth erupt before upper teeth, and that the first permanent tooth that appears in the mouth is the first lower molar.