Germ-line TCR genes from 41 Singaporean Chinese patients with nasopharyngeal carcinoma and 54 Singapore Chinese normal subjects were investigated by restriction fragment length polymorphism (RFLP) analysis. Genomic DNA from BLCLs of patients and normal subjects was digested with the restriction endonucleases BamHI, EcoRI, HindIII, TaqI, transferred to nylon membrane by the Southern-blot technique and hybridized with radioactively labelled TCR cDNA probes. When the combination of BamHI/V beta II was used, NPC patients had a lower frequency of the 25/25-kb allelic pattern and a higher frequency of the 20-kb fragment compared to controls. With the combination of TaqI/V beta 8, the 4.3/3.2-kb fragment allelic frequency was lower in total NPC but particularly in patients with HLA B46. The result suggested that TCR restriction may be important in the pathogenesis of NPC.