In this article, we discuss the issues of angioimmunoblastic T-cell lymphoma diagnosis, particularly the PCR-based methods of clonality detection. Assessments of T-and B-cell clonality was based on TCRG (Vg-Jg), TCRB (Vb-Jb, Db-Jb), IGH (FR1, FR2, and FR3), IGK (Vk-Jk, Vk/intron-Kde), or IGL (Vl-Jl) gene rearrangements in 15 patients. Clonal TCRG gene rearrangements were found in 66.7 % of primary biopsy samples. The combined use of primers for TCRG and TCRB gene rearrangements confirmed T-cell monoclonal population in most cases (86.7 %). The rate of B-cell clonality detection was 26.6 %. The presence of B-cell clones was not associated with monoclonal secretion in the blood or detecting Epstein-Barr virus positive B-cells in the biopsy samples. PCR-based clonality analysis is an important step in diagnosis of angioimmunoblastic T-cell lymphoma that enables identifying monoclonal origin of T-lymphocytes in most cases. However, when interpreting the results obtained by this method, it is necessary to consider the possibility of detecting B-cell monoclonal products of unclear origin.