Background: Lead is a metal that has been used by humans since ancient times and it’s over dosage causes an important environmental and professional toxicity. The aim of this study was to evaluate the effectiveness of single therapy with Ethylene diamine tetra acetic acid (EDTA) in lead poisoning.Methods: The study population was all patients with suspected lead poisoning were admitted to Baharloo hospital in Iran from January 20, 2005 to March 21, 2006. Diagnosis of lead poisoning was confirmed after history taking, clinical examinations and blood lead level. After obtaining informed consent, the patients were enrolled in our study. Allowed lead level was considered < 50 µg/dl. These patients were hospitalized for 5 days and treated with EDTA (1 g every 12 hours via slow intravenous infusion). CBC, urea, creatinine, liver function tests, coagulation tests and biochemical tests including glucose, lipids, electrolytes and uric acid, urinalysis, and urine volume was measured daily. The patients would be excluded if there were any contraindication for EDTA treatment, hepatic encephalopathy and blood lead level over than 150 µg/dl were considered as the exclusion criteria. All patients’ blood lead level was measured again 10 and 30 days after treatment. To analyze data, Wilcoxon test and SPSS software (version 16) were used.Findings: Forty one patients were studied. All were male. The patients’ mean age was 32 ± 6 years. The patients’ average blood lead level was 110.3 ± 5 37 µg/dl before the treatment. The patients’ average blood lead level was 63.4 ± 27.1 µg/dl ten days after treatment and 79.3 ± 28 µg/dl one month after treatment. The patients’ average blood lead level decreased significantly 10 days and one month after the treatment compared to begining (P < 0.001 and P < 0.012 respectively).Conclusion: EDTA is an effective drug for the treatment of patients with lead poisoning as single therapy.