In the recent years, the sea port industry including six groups of ports has been strongly developing and playing a critical role in Vietnam's economy. The volume of container cargo through Vietnam's port system has greatly increased from 98 thousands TEUs in 1999 to 15 millions TEUs in 2019 (Vietnam Seaports Association, 2019). Modern and efficienct container terminals have become one of the most significant current discussions in keeping pace with the speedily rising demand of container cargo services. Hai Phong, one of the two largest port system in Vietnam, is the area containing the biggest container terminals in the Northern of Vietnam with nearly 100% container throughput of this region. Several studies have been made to investigate Vietnam's container terminals performance. Of those that have, some of them have evaluated the efficiceny of major terminals in Vietnam, others have focused on the Northern port system with only simple methods.

Hence, this study seeks to investigate the relative efficiency of fifteen container terminals in Hai Phong over ten year period (2010 - 2019). A set of data envelopment analysis (DEA) methods were used. First, window DEA was carried out to investigate dynamic changes in efficiency among the 15 container terminals on the basis of data spanning the period 2010 to 2019. Afterwards, two basic models, namely, DEA CCR (Charnes-Cooper-Rhodes) and DEA BCC (Banker-Charnes-Cooper), were used to examine the terminals' scale of efficiency in 2019. Finally, a detailed ranking comparison of all the terminals for 2019 was performed using a slacks-based measure of super efficiency in DEA. The window DEA results indicated that throughout the 10-year period, the most efficiently performing terminal was the Green Terminal, followed by Dinh Vu, Hai An, and PTSC Dinh Vu. In 2019, the Vip Green Terminal was the most efficient, whereas several terminals, such as Transvina, Doan Xa, Tan Cang 189, Tan Cang 128, Chua Ve, and Nam Hai, suffered tremendous scale-related losses. This study offers important insights into the comprehensive performance of 15 container terminals in Hai Phong. Changes in efficiency over 10 years were investigated, after which the terminals were ranked for 2019. These results play a crucial role in helping concerned stakeholders determine strategic decisions.