We present the case of a man affected by an unclassified mature B-cell neoplasm with a bone marrow culture stimulated with TPA showing a 46,XY, t(11;13)(q13;q14)[14]/46,XY [6] karyotype. Fluorescent in situ hybridization demonstrated that the BCL1 oncogene is translocated (not rearranged) to chromosome band 13q14 and that a copy of D13S319 locus is deleted. To our knowledge, this is the first reported case with this novel cytogenetic aberration.