Abstract: In this research we exposed four day old seedlings of Zea mays were exposed to different concentrations of 0.25, 0.5, 1, 2 mM Pb(NO3)2 with pH 6 in the controlled condition. After 72 h the root of seedlings were harvested and the changes of fatty acids and total lipids percent of the samples were dermined. The percent of total lipids has been increased specially in 2mM Pb treatment. It was suggested that this was not because of inducing the process of lipids synthesis, but it was due to inhibition of growth, loss of metabolism activities and metabolite synthesis. The changes of fatty acids indicated elevated amount of unsaturated linoleic and linolenic fatty acids; which are considered as a tolerance mechanism to protect membrane systems against oxidative and heavy metals stress. But increased level of K+-leakage according to Pb concentration referred to significant decline of membrane stability. So it was concluded that Pb is a major chemical pollutant that causes different damages to root cells structure and components and Zea mays is a Pb-tolerant plant with a high potential of adaptation mechanisms like producing higher unsaturated fatty acids and the ability of forming some advantious roots from the first node of shoot that helps it to tolerate stress conditions.