The aim of this study was to determine the main contributors to blood lead levels in a population of women from middle to low socioeconomic status in the southwestern part of Mexico City. Within this area, the authors selected a random sample of 200 women. Age ranged from 21 to 57 years, with a mean of 36 years. Among 99 women who agreed to participate in this study, blood lead levels ranged from 1 to 52 micrograms/dL, with a mean of 10.6 micrograms/dL. Five percent of the women had a blood lead level over 25 micrograms/dL and 22% over 15 micrograms/dL. There was no significant trend in blood levels according to age. The main determinants of blood lead levels were higher socioeconomic status (presence of telephone in the house, t-test, p = 0.01) and using lead-glazed ceramics (LGC) to prepare food (t-test, p less than 0.005). There was a significant increasing trend in blood lead levels with increasing frequency of consumption of food prepared in LGC (test for trend, p = 0.0008). Among the dishes prepared in LGC, the main determinant was the consumption of stew. Time spent outdoors and consumption of tap water and of canned food were not important determinants of blood lead levels. The population attributable risk of high blood level (less than 15 micrograms/dL) due to the use of LGC was 58%. These findings demonstrate the major role of traditional pottery as a contributor to blood lead levels in this population and emphasize the need for interventions to produce lead-free pottery.