Lead is one of the earliest heavy metals discovered by human being. Among the environmental disease lead toxicity is one of the important environmental disease and its effect on the human body are overwhelming. There is almost no human body function which is not affected by lead toxicity. In this chapter I tried to elaborate briefly different sources exposure, toxicity, diagnosis, symptoms of lead poisoning and its treatment. The symptoms of chronic and acute lead toxicity, effect of lead toxicity in human body such as hemato toxicity, neurotoxicity, renal toxicity, cardiovascular toxicity, bone toxicity etc. have been discussed here. Apart from lead toxicity in human body the treatment of lead poisoning by different chelators like BAL, DMSA, diagnosis process like blood test, x-ray diagnosis have also been discussed.