When the PCR products amplified by the primers prepared at the 11th HLA Workshop (DQBAMP-A, DQBAMP-B) were analyzed directly by the SSCP method, one or two pairs of characteristic bands were detected other than those attributed to DQB1, and a total of three kind of paired bands were detected. To confirm that these bands were allelic genes of DQB2, the corresponding bands were isolated by cloning, and their base sequences were determined. The base sequence of one of them was in agreement with that of DX beta, which has already been described, and the characteristic 3-base defect was noted by comparison with the base sequence of DQB1. The same 3-base defect was noted also in the other two kinds. One-base substitution was present in each of the three kinds of base sequence, and they were confirmed to be allelic genes of DQB2. In DQB1 typing by the PCR/SSCP method of Carrington et al., treatment with the restriction enzyme Alu 1 is needed to eliminate DQB2. However, the use of this enzyme was theoretically demonstrated to be inappropriate, because it degraded the DQB1*0401 gene.