The mechanism of lead toxicity in human erythroid precursor cells (EPCs) is the main aim of this research. Abnormal development of EPCs, the imma red blood cells, may involve with lead induced anemia. Human EPCs, the model in this study, were prepared by two-phase liquid culture (TPLC) technique. Highly purified EPCs (>90%) and substantial numbers of the cells (30.46 +-19.48x10[superscript 6] cells/blood unit) were obtained from this technique. By using TPLC system, the early stage of EPCs obtained on day 7 of secondary phase were cultured in the presence of lead acetate. Morphological study showed that lead could inhibit EPC survival by inducing the cell cytolysis and apoptosis. The inhibition was time and dose-dependent. Marked effect of lead on EPC survival was at lead acetate concentration >= 1ppm. Flow cytometric analysis was used to detect apoptotic cells by monitoring the binding of fluorescence labeled annexin V to phosphatidylserine on the outer memberane of apoptotic cells. The study showed that lead could induce apoptosis in EPCs in time and dose-dependent manner at lead concentration >=1 ppm. These findings suggest new aspect of lead inducted anemia besides the impairment of hemoglobin synthesis and shortened life span of erythrocytes, lead induced apoptosis in human EPCs resulting in the inhibition of EPC survival may ne another mechanism of lead induced anemia.