The research was conducted to assess the biogas utilization and quality of wastewater from biogas structure in Thai Nguyen city. The results showed that Thai Nguyen city had 571 households and farms using bioĐas-structures of which there were 30 biogas-stuctures (5.25 percent) with the volume more than 20 m , 47 biogas-stuctures (8.23 percent) with the volume from 15 to 20 m3 and the others having volume below 15 m3. Most of the households and farms used biogas for cooking and lighting. The waste of biogas-stuctures was used for planting (vegetable, tea, etc) and raising fish. Regarding to quality of waste water from biogas-structure, COD factor has been 3.75 to 38.94 times higher in comparision with Vietnam environmental standards, the others have been lower than the standards.