Using the polymerase chain reaction (PCR) and hybridization with oligonucleotide probes, we analyzed the distribution of DPB1 alleles in 99 healthy unrelated individuals from the city of Guangzhou (Canton), South China. Twelve different DPB1 alleles were found in this panel. The most common allele was DPBI*0501 (62.6 %). Other major alleles detected included DPB1 *02 (DPBI*0201 and DPBI*0202), DPBI*1301, DPBI* 0401, and a recently described allele, designated DPBl*2101. The hybridization pattern of DPBl*2101 showed that this allele shared sequences with DPBl*0301 and DPBl*0601 in the A and F hypervariable regions, while the C, D, and E regions were identical to those of DPBI*0202. DPBI*2101 was observed in 11% of the subjects tested. It was found to be in strong linkage disequilibrium with DRBl*1202. In family studies, segregation of the haplotype DRBI*1202, DRB3*0301, DQAl*0601, DQBl*0301, DPBl*2101 was observed. The second exon of DPBI*2101 was sequenced from codon 8 to codon 90 and the sequence, inferred from the pattern of hybridization, was confirmed. DPBI*0301, DPBI*0402, DPBI*OIO1, DPBI*1401, DPBI*1901, and another recently recognized allele, now designated DPBl*2401, were detected with low frequencies. DPBl*2401 had the same hybridization pattern as DPBI*0501 except for a probe that matches codons 85-90. In this region, DPBl*2401 encoded the amino acid sequence GPMTLQ instead of EAVTLQ as in DPB1 "0501.