Childhood lymphoblastic leukemia is considered the most common malignant disease affecting children. Many theories have been postulated to explain the etiology of this diverse disease. Our study was to spot the incidence of some viral infections in ALL, the possible etiological relation between them. The study included 30 patients newly diagnosed ALL from the NCI in Cairo, 16 males, 14 females with age range from 15 month – 6 years .All of them with negative history of blood transfusion. They were subjected to complete medical examination, investigations including ESR, CBC, bone marrow biopsy. PCR for hepatitis B, hepatitis C, and Epstein Barr viruses. The PCR results for the studied viruses were positive in about 50% of the chosen ALL children (15/30), of them 10% were positive for Epstein Barr virus (3/30), 10% were positive for hepatitis B virus (3/30), 23% were positive for hepatitis C virus (7/30), while the incidence of mixed hepatitis B and C was 7% (2/30). The viral infections as an etiological factor for childhood ALL is still debatable but the results of our study were more towards this possibility as the high incidence of the studied viruses among the chosen group (50%) might be a further support to this theory . It also points to the importance of the obligatory vaccinations as mean of prophylaxis against these infections and the close follow up to these patients to spot the fate of these viral infections.We recommend another studies concerning other battery of viruses may give more light to the viral etiology theory