The physical state of Epstein Barr virus (EBV) DNA was analyzed in the Burkitt's lymphoma (BL) cell line BL60 and in the autologous EBV-immortalized lymphoblastoid cell line (LCL) IARC 277 by Gardella gel analysis, Southern blotting, and nonradioactive in situ hybridization to metaphase chromosomes. Although only episomal viral DNA was detected in the LCL, the 6-12 copies of EBV DNA in the BL cell line are integrated in one site of the host cell genome. The integration site is located near the breakpoint of a translocation 11;19 which is present in this cell line in addition to the BL-specific t(8;22).