This paper examines interlingual errors in Vietnamese English from the survey on forty Tra Vinh University (TVU) students,Vietnam, which aims to compare their differences in grammar and how the errors have occurred owing to the Vietnamese interference onto English. The error analysis focuses upon four categories: inflectional morphosyntax, copular ‘to be’, article, and word order. The findings have indicated that in inflectional morphosyntax, the interlingual errors were found in tense and aspect (85%), subject-verb agreement (100%), and noun plural inflection (97.5%), where the suffixal morphemes ‘-s’ and the tense and aspect features were omitted. In a similar way, copulas ‘to be’ were omitted before adjective with 30%. The third category is article when the interlingual errors (100%) occurred in two different ways: omission and confusion. Finally, the three subcategories of interlingual errors in word order were found including noun modifier position within a noun phrase (100%), adjective position within a noun phrase (97.5%), and adverb position within a verb phrase (40%). This paper also provides guidelines and solutions to more successful English use in Vietnamese context and proposes a potential study at lexicon level.