Ungrammaticality is a phenomenon that is not associated with the use of the mother tongue. This is because the mother tongue is naturally acquired in the environment of its domain. This paper sets out to provide evidence of the possibility of ungrammaticality in the mother tongue. But this exists as result of interference from dialectal varieties of the Igbo language. The research work identifies some of the ungrammaticalities observed in the standard Igbo which represent dialectal features. The data for the research were collected through observation of native speakers’ speech event, and the analysis was done using the approved principles for the standard Igbo. The errors identified include: personifying inanimate things, impersonifying man, improper application of plural markers, indirect repetitions otherwise known as tautology, improper use of the first person singular pronoun and wrong use of some diction, among others. The researcher recommends that native speakers should adhere to the principles of the standard form of the language because any native speaker is a potential informant to linguists and language learners. This paper therefore contributes immensely to the goal of better teaching and learning of the standard Igbo.