OBJECTIVE: To establish the method of screening the susceptibility to childhood lead poisoning by filter paper. METHODS: The genomic DNA from normal children was extracted with Chelex 100 (the filter paper method) and the chloroform method. The quantity of DNA recovered by the two methods were compared. A rapid PCR based method for precise σ aminolevulinate dehydratase (ALAD) genotyping was also established. RESULTS: The quantity of DNA recovered by the filter paper method (with Chelex 100) and the chloroform method was 17.1 μg/ml and 17.5 μg/ml , respectively. There was no difference between the two methods. Both the two methods were of great practical value in the screening of ALAD genotype in high risk people, but the filter paper method was less sensitive for PCR amplification than the chloroform method.CONCLUSIONS:Technically the filter paper method might be more reliable in screening the susceptibility to childhood lead poisoning.