The European Biomedicine and Health (BIOMED-2) Concerted Action Project BMH4-CT98-3936 has defined standardized protocols for polymerase chain reaction (PCR) amplification of different loci of the T-cell receptor (TCR) and immunoglobulin (Ig) genes with a view to achieving greater sensitivity and specificity in the assessment of clonality of lymphoid neoplasms. To assess T-cell clonality, analysis of TCRbeta gene and TCRdelta rearrangements (useful in cases of Tgammadelta + cell neoplasms) is proposed alongside that of TCRgamma. For analysis of B-cell clonality, along with the framework (FR) III segment of the IgH gene, other segments are studied (FRI, FRII) in addition to Igl and Igk genes or incomplete DJ rearrangements of the IgH gene and the k deleting element. The results of the amplification are read using automatic reading systems (GeneScan) or using a heteroduplex system.