A rapid and sensitive technique to determine lead in trace level present in aluminium based alloys by flame atomic absorption spectroscopic technique (AAS) is described. It is free from aluminium and silicon spectral interferences. The method is free from associated alloying elements. Lead was determined at 283.3 nm using air-acetylene flame. The value of relative standard deviation (r.s.d.) of lead, in case of high silicon containing samples is found to be 2.545% and that for low ones 10-12% respectively. The standard deviation values were +/-0.0014 and +/-0.0016 respectively. A threshold limit of concentration of aluminium and silicon for the determination of lead in final analyte solution has been described and this has been correlated with the sample weight to be taken for analysis.