Atayal, one of the Formosan languages, consists of two major dialect groups, namely, Squiiq and C'uli'. Tsuchida (1980) proposes three linguistic criteria phonological, lexical and morphological for classifying Squiiq and C'uli' as distinctAtayal dialects. The present paper attempts to provide some syntactic evidence forsuch classification. The Squiiq dialect investigated here is spoken in Wulai, Taipei Prefecture (hereafterWu), and the C'uli' dialect under discussion is that of Mayrinax, Miaoli Prefecture(hereafter Ma). Below are some structural characteristics of the two Atayal dialects:(1) pronominal systems: While Wu has four sets of pronominal forms, i.e. Bound Nominative pronouns, Bound Genitive pronouns. Free Locative pronouns and Free Nominative pronouns, Ma has only three, lacking the Locative pronouns. Also, the distribution and semantics of these pronouns are different.(2) case/prenominal markers: While Ma requires the presence of case markers in utterances, Wu seldom requires these prenominal markers. Thus, word order plays a very important role in Wu.(3) tense-aspect systems: While Ma often utilizes affixes or/and reduplication to illustrate different tenses/aspects, Wu uses affixes or/and auxiliaries, but not reduplication.(4)negative constructions: Both Ma and Wu have two negators in declarative sentences, but in imperative constructions, Ma has two negators while there is only one in Wu. As shown above, Wulai Atayal and Mayrinax Atayal share some syntactic featuresand display some differences as well. Such syntactic similarities and differences furthersupport that they are two different dialects of the same language.