The objective of this study was to determine the level of organochlorine pesticides in maternal milk of women living in urban and rural areas in central Mexico. High levels of the DDT ( 1,1,1 -trichloro -2,2 -bis ( p -chlorophenyl ) ethane ) and metabolites, p,p H -DDT ( 1.83, 0.66 and 3.13 mg / kg ) and p,p H -DDE ( 2.49, 4.28 and 13.32 mg / kg ) , were encountered for Mexico City, Cuernavaca and rural Morelos, respectively. As was expected, the highest levels of exposure to these pesticides were found in the rural areas of the State of Morelos.