Speaking test topics chosen according to the test-takers' area of expertise can be used to assess their speaking abilities to talk about general background knowledge or their academic subject areas. Recent studies have indicated that the topic choice affects testing performance on the oral tests, but provided inclusive results regarding the effect of general and specific-field topics on the test takers' oral performance. The aim of this research study is to investigate what type of oral assessment instruments and more specifically what topics and tasks might be best for the purpose of assessing Vietnamese faculty's oral English proficiency in the academic workplace. The results showed no significant difference in the faculty speaking performance on the general and academic field-specific topics. The findings of the research have important implications for assessing oral production in specific-purpose language testing and for providing information about the needs of Vietnamese faculty for training in spoken English for the academic workplace.