The objective of this study is to assess the flow regime changes in the Mekong River, Vietnam under human-induced intervention for a period of 2000-2014 by usingIndicators of HydrologicAlteration (IHA) and Range of Variability Approach (RVA) methods. IHA consists of 33 biologically relevant hydrologic parameters which are composed into five major groups, describing:(1) magnitude, (2) timing, (3) frequency, (4) duration and (5) rate of change. The historical flow data in the period of 2000-2014 at 4 stations (Tan Chau and Chau Doc in the upstream; Vam Nao and Can Tho in the downstream) was examined to assess the impacts of water infrastructures (semi-dykes and full-dykes) on flow regimes by comparing two periods: pre-dykes (2000-2005) and post-dykes (2006-2014). The results show that there are significant changes of hydrological regime in the Mekong River at all 4 researched stations with the Hydrologic Alteration (HA) of 61%, 53%, 56% and 58%, respectively. Especially in the Basac River, the frequency has been found to be strongly altered with their HA of 83%at Chau Doc and 117%at Can Tho stations.At these stations, the magnitude have changeddramatically, particularly in December in which the HA is increased up to 133%. In addition, the numerous alterations of timing, frequency, and rate of change indicatorsat Can Tho and Chau Doc stations have been also found. These changes may cause serious habitat alterations; therefore, hydrological regimes should be kept in an appropriate range.