Lead, one of the most widely used metals because of its beneficial physical properties, has been reported to adversely influence several different organs and organ systems. The aim of the present study was to examine the effect of lead exposure on liver and renal function and haematologic parameters. This was a case-cohort study comparing adults with occupational, environmental or opium-related lead exposure with blood lead levels [BLL] >10μg/dL (High blood lead level (HBLL) group and age- and gender-matched normal healthy individuals (Low blood lead level [LBLL] group with BLL <10μg/dL). The complete blood count and concentrations of serum creatinine, urea, aspartate aminotransferase (AST), alanine aminotransferase (ALT) were recorded for subsequent investigation. The mean BLL was significantly higher in the HBLL than in the LBLL groups (51.36±44.72 vs 4.17±1.97µg/dL). The Spearman's rho revealed a significant association between BLL and urea (r=0.25, P<0.001), creatinine (r=0.16, P=0.02), AST (r=0.42, P<0.001) and ALT (r=0.27, P<0.001). The median [IQR] serum urea (34mg/dL [27-221]) vs (30 [27-36]), creatinine (0.9mg/dL [0.8-1]) vs (0.8 [0.7-0.9]), ALT (25mg/dL [16-49]) vs (22 [16-30]) and AST concentrations (29mg/dL [20-42]) vs (20 [18-24]) were all significantly higher (P<0.05) in the HBLL group compared to the LBLL group. The median [IQR] haemoglobin (12.6g/dL [10.4-15.4]) vs (15.2 [14.6-16.3] and haematocrit (36.9% [31-44.8]) vs (45.6 [43.6-48.2]) were both significantly lower (P<0.001) in the HBLL group than in the LBLL group. The results indicated that people with chronic lead exposure with BLLs greater than 10μg/dL are at risk of renal, liver and haematologic impairments.