Ninety- nine blood samples were collected in Egypt during 2003 – 2004 (85 males' and 14 female's) aged between twenty five and sixty years old from both diagnosed liver and bladder cancer patients in addition to high-risk people to these types of cancers such as hepatitis C virus and chronic bilharzias as well as apparently healthy people as a control. The collected blood samples passed through separation of serum, extraction, evaporation, concentration and determination using gas liquid chromatography equipped with electron capture detector. The monitoring of 14 organochlorine pesticides, characterized by their long  persistence in human tissues which are HCB, alpha-HCH, beta-HCH, gamma-HCH, delta-HCH, Aldrin, Dieldrin, Heptachlor and Heptachlor Epoxide, Endrin, o,p'-DDT, p,p'-DDT, p,p'-DDE and p,p'-DDD and polychlorinated biphenyls congeners (PCB's) no. 28, 52, 101, 118, 138, 153, and 180. The results showed that only DDT (mainly p,p`-DDE ),HCH (mainly beta-HCH) and HCB were detected with high frequency 97% and 77.8 and 2% respectively, while polychlorinated biphenyls residues and other chlorinated pesticides were not detected in any analyzed blood samples. The findings indicate that the higher significant levels of total HCH (mainly beta-HCH) and total DDT (mainly p,p'-DDE) in bilharzias and hepatitis C virus with respect to those found in apparently healthy subjects as a control which indicate the possible role of chlorinated pesticides in neoplastic transformation of bladder and liver as well.