Although the application of business intelligence (BI) system has increased recently, the critical success factors (CSFs) of BI system implementation remain poorly understood. Therefore, understanding CSFs for BI system is necessary for a company to be successful in implementing a BI system. Currently, the number of business successfully implemented BI in Vietnam is still limited. In order to understand the current situation of BI implementation in Vietnam, case study method has been used. Based on the research framework developed by Yeoh & Koronios, in-depth interviews have been conducted with 4 Vietnamese companies, who already implemented BI system. The main result of this study helps to extract the lessons learnt from 4 cases to rank the importance of CSFs for BI implementation in Vietnam context. Based on this result, recommendations were made for increasing the probability of successfully implementing BI system in Vietnam and other countries with similar conditions.