This study attempts to explore the impact of blended learning (BL) approach and online learning (OL) approach on student achievements in a fundamental course at a polytechnic in Vietnam. Secondary data were collected by the Academic Affairs Office. A simple statistical analysis method was employed to process the data. The findings revealed that BL approach implementation left a positive impact on student achievements since the pass rate remained high, the fail rate and ineligibility rate were satisfactory over the studied period. Meanwhile, the data of the pass rate and fail rate in the OL course proved that this approach had not gained success compared to prior expectation when there was a decision to transform from BL approach to OL approach in teaching fundamental courses at the polytechnic. However, the positive ineligibility rate in the studied OL fundamental course suggested that OL approach would be appropriate in teaching this course provided that further research should be done to figure out the issues and offer the resolutions. © 2020 ACM.