Abstract: Transfusion Transmitted Virus (TTV) is a naked, single stranded DNA virus, which has been discovered in the serum of a patient with post-transfusion hepatitis of unknown etiology. TTV infection is widespread in the general population, however, the mode of its transmission is still unclear. This study was conducted to search for TTV-DNA positivity rates and to evaluate its clinical significance in both Egyptian polytransfused thalassemic children and healthy children. Serum samples from 33 polytransfused thalassemic children and 30 healthy children were studied for the presence of TTV-DNA by nested PCR using primer sets generated from the untranslated region (UTR) of the viral genome. TTV-DNA was found positive in 39.4% of polytransfused children versus 40% of healthy children, the high rate of viremia observed in healthy children indicates that transfusion route is not the only mode of TTV spread. 60.6 % of the polytransfused group were HCV positive. Fifty five percent of HCV positive cases showed TTV-DNA positivity, suggesting common route of infection. No significant difference between ALT and AST values in TTV-DNA positive polytransfused children compared to negative cases. ALT and AST values were statistically significantly higher in HCV positive patients compared to negative cases. On the other hand no significant difference was observed of ALT and AST values in isolated HCV infection versus TTV and HCV co-infection. Thus although TTV infection is quite common among Egyptian, no convincing evidence was found to support its involvement in the pathogenesis of hepatitis in children, more data are still needed for a better understanding of the natural history of TTV infection.