We present data on significant fetal exposure to lead (Pb), mercury (Hg) and cadmium (Cd), based on meconium analysis, and the effects of this exposure. METHODS: Infants were randomly recruited from 7 hospital nurseries in Manila, Philippines. Meconium was anonymously obtained from each infant and analyzed for lead (Pb), mercury (Hg), cadmium (Cd) by atomic absorption spectrometry. Pertinent clinical and demographic data were taken from the maternal and neonatal records. RESULTS: A total of 422 maternal infant dyads were studied. Meconium was positive (% of total infants tested) for Pb(26.9%), Hg (83.1%) & Cd (8.5%). Mean (sd) conc (per g meconium) were: Pb= 63.9 + 74.5 mcgg/g (range=4.1-301.5); Hg =1.9 + 2.3 ng/g (range= 0.2-17.5); Cd = 7.02 + 3.51 mcg/g (range= 1.1-13.7). The Pb (+) meconium was associated with a significant (p<0.03) increase in the incidence of meconium stained fluid (15 vs 5%), multiple gestation (12 vs 4%), birth weight <2.5 kg (13 vs 7%); SGA (9 vs 3%) and parity >3 (15 vs 7%). High Pb conc in meconium(mean=254 mg/g) was also associated with lower gestation (mean=35.6 wks, p<0.05, ANOVA). The Hg (+) meconium was associated with a significant(p<0.05) increase in incidence of gestation < 37 wks (16.2 vs 5.6%) and head circ <33 cm (59 vs 41%). The Cd (+0 meconium was associated with a significant (p<0.02) increase in the incidence of parity >3 (22 vs 8%) and decrease in neonatal jaundice (11 vs 36%). We conclude that meconium analysis is an easy and useful tool to detect fetal exposure to environmental toxins, e.g., heavy metals. High prevalence and significant hazards from such exposure were observed in the population studied.