The comparative characteristic of the reproduction of adenovirus serotypes 2 and 5 (HAdV-C2 and -C5) in the various lymphoblastoid cell lines were studied. Rapid formation of infectious viruses in Raji, MP-1, Namalwa, BJAB, MT4 and Jurkat cells was marked and it was found to be close to the level of viruses during reproduction in permissive Hep-2 epithelial cells. Yield of infective adenovirus was low in B95-8 cells, which were chronically infected with Epstein-Barr virus (EBV). This may indicate the interference of Ad with EBV during super-infection. The CEM cells produced chronically low amounts of human adenovirus serotype 2.