A cell line named ROS-50 (Rotterdam suspension cell line no. 50) has been established from peripheral blood of a 69-year-old male with acute lymphoblastic leukemia (FAB type L3). Among the aberrations, cytogenetic analysis showed the presence of 14q+, 18q-, and two 8q- marker chromosomes. With fluorescence in situ hybridization (FISH) we characterized the chromosomal translocations, t(8;14) and t(14;18), in which the same chromosome 14 is involved. PCR analysis demonstrated the presence of on IGH-BCL2 rearrangement with a breakpoint in the minor cluster region (mcr) confirming the t(14;18) characteristic for follicular lymphoma. Additional studies showed high expression of BCL2 protein, an early B-cell immunophenotype, and an unusual pattern of IGH gene rearrangement.