Twenty-eight Burkitt's lymphoma(s) (BL) cell lines were analyzed with anti-human immunoglobulins and monoclonal antibodies: Y29/55, B1, and BA1 are slightly different pan-B-reagents; TU1 and BL13 are two discriminating markers of the follicle; RFT1 is a pan-T-reagent expressed on the follicle mantle; AL2 reacts with the common acute lymphoblastic leukemia antigen gp100; and 38:13 recognizes a BL-associated antigen. Those lines were classified into 3 groups according to their membrane phenotype. In the first 2 groups, cell lines were derived from BL of germinal center origin, whereas in the last group they were established from BL cells originating in the bone marrow. All cell lines in the last group were from Caucasian BL, whereas lines from African BL of a high-incidence area were in group 1. North African cases were in group 2. Those distinct subgroups were not related specifically to the reactivity with Epstein-Barr virus nuclear antigen, the type of chromosomal translocation, or the clinical features. The variations induced by growth culture as well as the clinical implications were discussed.