This study investigates the accuracy of the use of Korean honorifics by Korean Learners in Vietnam. From November 2017 to December 2017, 98 elementary, intermediate, and advanced Korean Learners at Hue University of Foreign Languages in Vietnam were given a survey to find the errors pattern when they use Korean honorifics. Questionnaire results were analyzed using TestAn 1.0 for Windows, a statistical testing tool. Results showed that the students made vocabulary errors such as respect to someone by using ‘nim(님)’ and ‘special vocabularies(특수 어휘)’. For example, we can use ‘nim’ for 선생님(teacher), 기사님(driver), etc. Also, general vocabularies such as 집(home), 이(teeth), 자다(sleep), 있다(stay) will be changed into the special vocabularies such as 댁(home), 치아(teeth), 주무시다(sleep), 계시다(stay). And the students also made grammatical errors such as using ‘-(으)시’- prefinal ending(선어말어미) after verbs, doing something for someone (Verb+ 아/어 주다), and referencing the third person. Examples of errors in referencing the third person include student A referencing a teacher to student B, or a mother referencing her father-in-law to her son. In addition, this study not only found the types of errors in Vietnamese learners using the Korean honorifics, but also identified the causes of various errors in their use of Korean honorifics. Using a comparative linguistic point of view, this study provides basic data about teaching and learning the honorific method by examining the causes of the errors made by Korean Learners in Vietnam.