OBJECTIVE: Mismatch negativity (MMN) was originally shown in a passive auditory oddball paradigm to be generated by any acoustical change. More recently, it has been applied to the study of higher order linguistic levels including the morphosyntactic level in spoken language comprehension. In this study, we present two MMN experiments to determine whether morphosyntactic features are involved in the representations underlying the morphosyntactic processing. METHODS: We reported two MMN experiments in passive auditory oddball paradigm with pairs of French words, a pronoun and a verb, differing in agreement grammaticality. These two experiments differed in the number of morphosyntactic features producing agreement violations, i.e. either of person and number features or of person feature. RESULTS: We observed no effect of grammaticality on the MMN response for these two experiments. CONCLUSIONS: Our studies highlight the difficulties encountered in studying morphosyntactic level with the passive auditory oddball paradigm. SIGNIFICANCE: The reasons for our inability to replicate previous studies are presented, and methodological changes in the passive auditory oddball paradigm are proposed to better tap into the morphosyntactic level.