Abstract: By way of chronotoxi cology,we studied the effect of zinc on the circadian rhythms of lipid peroxidation induced by lead in rats.The result showed that the contents of lipid peroxide(LPO) in normal rats had cilcadian rhythms,with 14:14 as its aorometron and 02:14 as its bathymetron.Upon intoxication with different doses of acetate lead,the LPO content in exposed groups were higher than those in expostrol groups (P<0.01),and the LPO circadion rhythms were all destroyed,Which showed a signflcant dose-response relationship.