It has been believed that replacement of the endogenous promoter and the non-coding first exon of the BCL6 gene by a sequence derived from the translocational partner gene is a main mechanism of the BCL6 dysregulation resulting from translocation. In this study, we found that reciprocal BCL6 translocation led to the expression of not only the 5'-partner/BCL6-3' fusion transcripts but also the 5'-BCL6/partner-3' fusion transcripts, suggesting that reciprocal 5'-BCL6/partner-3' fusion genes are transcriptionally active. These findings raise the possibility that reciprocal BCL-6 translocation may lead to dysregulation of the partner gene as well as the BCL6 gene.