This study attempts to investigate how dialectal differences of English affect the identification of English vowels by native and nonnative speakers of English. Served as listeners were native speakers of New Zealand English and Japanese. They heard and identified /i, ɪ, eɪ, ɛ, æ, ɑ, ʌ/ uttered by native speakers of New Zealand and American English. Repeated-measures ANOVAs were performed, respectively, for each listener group. The results revealed that there was no significant main effect of dialect (p = 0.013), but a main effects of vowels was found significant (p≺0.001). An interaction between dialect x vowels was also significant (p≺0.001). Pairwise comparisons revealed that NZ listeners identified NZ English /ɪ/, /ɑ/, /ʌ/ better than AM English counterparts (p≺0.05), but they identified AM English /æ/, /ɛ/ better than NZ English counterparts (p≺0.05). Native Japanese listeners, on the other hand, identified AM English vowels significantly better than NZ English vowels (p≺0.001). Particularly, they identified /i, ɪ, ɛ, æ/ uttered by AM English talkers than those uttered by NZ English talkers. However, native Japanese listeners identified NZ English /ɑ/ better than American English counterpart(p≺0.05).