The goal of this study, part of the PERSOTHER project, is the implementation a new ancillary technique - fluorescent in situ hybridization (FISH) - in Burkitt lymphoma (BL) diagnosis, for the first time in our country. BL is a B-cell lymphoma with a highly aggressive clinical course. Three clinical variants of BL are recognized: endemic BL (in equatorial Africa), sporadic (throughout the world) and immunodeficiency-associated BL. The 2008 World Health Organization (WHO) Classification described a new category of B-cell lymphoma, unclassifiable, with intermediate features between diffuse large B-cell lymphoma (DLBCL) and BL. Because the treatment of BL is very aggressive, with high doses chemotherapy, an accurate diagnosis is required. Cytology, morphology and immunophenotype (CD20+, CD10+, BCL6+, BCL2-, Ki67 98-100%) are typical for BL. Most of the cases have MYC translocation at band 8q24 to the IgH region, 14q32. The demonstration of MYC translocation is necessary for BL diagnosis and differential with DLBCL and borderline cases. 22 cases of BL were evaluated by FISH for MYC translocation. 17 cases were positive, one case was negative and 4 cases were inconclusive. The results are concordant with the literature: the authors report about 10% MYC negative cases. In this cases micro-RNA (MiRNA-s) alterations may be implicated. The present study highlights the importance of FISH in BL diagnosis. It also identifies some of the technical difficulties of this method and it represents a basis for future routine diagnosis of selected BL cases.