B-cell CLL/lymphoma 6 member B protein is a protein that in humans is encoded by the BCL6B gene.

The deduced 474-amino acid protein contains an N-terminal POZ domain and 5 C-terminal zinc finger motifs. Bazf shares significant similarity in domain structure and amino acid sequence with BCL6, including complete conservation of a 17-amino acid sequence in the middle portion of the proteins. Northern blot analysis detected a 3.8-kb transcript in mouse heart and lung, and RT-PCR detected expression in all tissues examined. Bazf colocalized with Bcl6 within the nucleus of transfected mouse fibroblasts.