Speaking skill plays an important role in studying a foreign language, especially English. However, learners make a lot of errors in English speaking. The study was conducted to examine the the common mistakes learners had in English speaking. Two instruments were employed to collect data. First, eighty-three participants in four classes - Master of Business Administration (MBA) course 8 and 9 - responded a questionnaire with 4 questions and 45 closed statements. Second, four observation periods were conducted to supply more information to make clear and prove the common mistakes that learners had during the process of speaking. This was a quantitative and qualitative research. It gave a clear and specific view about errors in English speaking faced by MBA learners at Tay Do University as pronunciation (intonation, ending sounds, consonant cluster, and word stress) and grammar (articles, tenses, passive voice, and order of words).