The purpose of this study was to up-date the records concerning oral clefts (OCs) encountered at the Child Hospital of the Maternal Infantile Institute of the State of México, and to examine the association of predisposing factors. A retrospective study of the medical records of patients generated over a 5-year period was carried out. A total of 835 files were reviewed, representing 504 boys and 331 girls. The studied variables were the type of oral clefts and predisposing factors. Kendal correlations at P < or = 0.05 and chi-squared at P < or = 0.05 were used to find any associations between variables. The distribution of oral cleft was: cleft lip and palate (CLP) 70%, cleft palate (CP) 21%, cleft lip (CL) 8%, separate cleft lip and cleft palate 1%. The sex ratios were 1.7 for CLP, 1.7 for CL, and 1 for CP. Municipalities with ethnic groups as well as industrial, agricultural and pottery activities showed a high rate of prevalence. Although there was no significant association with birth weight, familial history of clefting, consanguinity, medication usage during pregnancy, or paternal occupational risk, the results suggested that the most severe clefts were proportionally related to these factors. A significant association with maternal and paternal age, abortion rate, and parity was found. Additionally, maternal agricultural activities suggested that pesticide exposure might be a factor.