In our previous study, a novel P[8] subtype, i.e., P[8]b was identified for human rotavirus strains MMC38 and MMC71 detected in Bangladesh, of which the P types could not be determined by conventional RT-PCR genotyping methods. In the present study, a modified multiplex RT-PCR method was developed to detect P[8]b as well as common human rotavirus P types. With this method, P[8]b was detected in three strains among the 26 rotavirus specimens which had been judged as mixed P types in the previous study in Bangladesh. The VP4 nucleotide sequences of these strains showed more than 98.9% identities to those of strains MMC38 and MMC71. The newly designed RT-PCR method was considered as useful for identifying P[8]b and avoiding misclassification by the conventional RT-PCR genotyping methods.