Vietnamese fisheries have long traditional development. They are operating under an open access fisheries regime with small scale, multi-species and multi-fishing gears. The number of fishing vessels, the total engine power and the total yield have been increasing continuously overtime; meanwhile the CPUE (catch per unit effort) have been reducing seriously. Vietnamese fisheries are facing overexploitation and declining resources especially regarding the inshore resources. One of the reasons leading to these problems is trawler operation, especially with onshore bottom trawlers. However, trawlers also account for a huge proportion in the total number vessels and the total catch. Thus, this study focus on evaluating economic efficiency of trawl fleets in Vietnam – the case of trawl fleets in Nha Trang city, Khanh Hoa province. 57 trawlers in Nha Trang, accounting for 13.7% of the total trawlers were investigated on costs and earnings data. The empirical results have shown that the owners of heterogeneous trawlers earn an average profit of 89.4 million VND corresponding to a profit margin of 12.8%. On average, all economic indicators are positive although there are some trawlers showing losses. The medium group (60 ≤ Hp < 90) is the most efficient group. The gross revenue was chosen as a proxy for fishing effort because of lack of catch information. The regression analysis shows that the numbers of fishing days, the circumference of the trawl mouth and engine power are the most important factors impacting on economic efficiency of Nha Trang trawl fisheries; meanwhile, the number of fishers is insignificant. Salter program application has shown that profit still generated in open access fisheries regime, particularly in the case of trawl fleets in Nha Trang. The study also shows the over investment on particular trawlers in Nha Trang which may lead to economic inefficiency.