The dietary behavior of immigrants starts changing upon their arrival in a new country. We evaluated changes in dietary quality of Vietnamese women immigrants in Korea and compared dietary quality with that of Korean women. Fifty-six Vietnamese women immigrants and 56 age-matched Korean women were recruited. Dietary quality were assessed using index of nutritional quality (INQ) and diet quality index-international (DQI-I). Dietary habits were assessed according to 4 dietary behaviors: a prudent, calorie control, dietary fat control, and sodium or salt control diet. DQI-I scores of Vietnamese immigrants decreased after immigration, especially the moderation score, although the variety score increased. Scores were significantly lower than those of Korean subjects (45.1 vs. 64.5; p < 0.001). Vietnamese women immigrants had significantly poorer nutrient balance and calorie intake control, although their fat and sodium control was better than that of Korean woman (p < 0.001). INQs of protein, niacin, phosphorus, iron, zinc were lower in immigrants who had lived longer in Korea than more recent immigrants (p < 0.05). Lower INQs of protein, fiber, vitamin A, B1, B6, C, folate, and phosphorus were related to higher body fat in Vietnamese immigrants (p < 0.05). In conclusion, dietary quality of Vietnamese immigrants decreased after migration, and dietary intake was inadequate compared with that of Korean women. In addition, diet quality of Vietnamese immigrants decreased with length of residence in Korea. There was a negative correlation between diet quality and body fat percent in Vietnamese women immigrants. Findings from this study may help improve diet quality and prevent obesity in Vietnam women immigrants.