Background. Dau Ha Chau is a seasonal fruit which has originated from selecting and propagating the local varieties of Baccaurea ramiflora Lour. in Vietnam. However, the time to harvest, the quality of the fresh fruit, and the ability to store it have not been evaluated sufficiently. The aim of this study was to assess the changes in bioactive compounds and antioxidant activity during fruit development and storage stages to evaluate the quality of fruit after harvest and under storage conditions in order to stabilize the fruit sources for the processing of dau Ha Chau products during the off-season. Materials and methods. Three development stages of dau Ha Chau (100, 115, and 130 days after fruit set) and four storage conditions (at 30, 4 and –20°C (whole fruit) and –20°C (peeled fruit)) were analyzed, as well as ascorbic, gallic acid (HPLC method), total phenolics (Folin-Ciocalteu), flavonoids content (AlCl3 complexation), and antioxidant activity (DPPH method). Results. Over three stages, the external color of fresh dau Ha Chau peel altered from light yellowish green (day 100) to pale yellow (day 130). The bioactive compounds and antioxidant activity (EC50) showed a concentration decline, with figures on day 130 reaching 826.26, 78.17 µg/mL, 157.89 mgGAE/L, 76.69 mgQE/L, and 614.36 mg/mL (EC50), respectively. While fresh dau Ha Chau, after being picked on day 130, retained their quality to 20 days at 30°C, with 407.66, 78.12 µg/mL, 117.07 mgGAE/mL, 55.29 mgQE/mL, and 1122.62 mg/mL (EC50), respectively, on day 20, those parameters at 4°C were kept to 30 days. The frozen storage at -20°C showed a slight decline in fruit quality after 6 months, but whole fruit preserved the quality better than peeled fruit. Conclusion. The results of this study are the first report on bioactive compounds and antioxidant activity of dau Ha Chau fruit during preharvest and postharvest stages and fruit storage capacity. This will be a source material based on which further assessments of fruit nutrition and health benefits for development in research, fresh fruit consumption, or the food-drink processing industry can be done