The present study describes the phenotypic and genotypic features of seven individual growth transformed, euploid-diploid EBV+ human B cell lines arisen spontaneously in vitro. The lines, obtained under general and standard culture conditions (un-manipulated), from seven individual bone marrow samples of 18 healthy young adults, Caucasian, of both sexes, display many traits of normal B cells and represent a mixture of EBV infected latently (latency type III) and producer cells (5-16% VCA+ by immunofluorescence) releasing seven individual different viral strains [Fruscalzo et al., 2001. DNA sequence heterogeneity within the Epstein-Barr virus family of repeats in the latent origin of replication. Gene 265, 165-173] similar to the B95-8 genotype as shown by results of Southern blot of BamHI-digested DNA fragment. These tests were planned to characterize more fully this panel of new bone marrow cell lines sharing normal B cell traits.