This bachelor thesis describes the introduction of a PCR-based System for the detection of clonality of malign B-cell lymphomas in the Center for Medical Genetics in the Hanusch Hospital. Considering that B-cell clonality is generally given in B-cell malignancies, it is possible to differentiate between benign (reactive) and malign lymphoproliferations through the analysis of B-cell populations regarding the presence of clonality. In order to establish this system, three primer sets were used, all of which were designed and published by the BIOMED-2 network for IGH-clonality assays. Appropriate multiplex PCR conditions and a suitable PCR protocol were determined using positive and negative controls. To this end, different PCR master mixes were compared and the ideal PCR conditions (annealing temperatures) of the primer sets were defined. Validation of the system was carried out by the analysis of blinded samples. Furthermore, the systems sensitivity was assessed through serial dilution of control samples. For the analysis of the PCR-products, both heteroduplex analysis and fragment analysis were carried out and compared. In closing, an overview in regards to possible further steps towards diagnostic application of the system is given, the results of the system validation are examined, and lastly, the relevance of clonality assays for diagnostic purposes is discussed.