Objective: Surveying the knowledge, attitude and behavior towards voluntary blood donation and the factors affecting to donation behavior of medical staff working at some hospitals in Ho Chi Minh city. Method: crosssectional study. Results: 53.6 percent of the respondents were at good level of knowledge aboutblood donation, there is no correspondence among knowledge, attitude and behaviour between people who did not give blood and donated blood. Saving lives (96.8 percent), being good for health (97.8 percent), the opportunity of receiving blood in need (95.8 percent), the movement (95.8 percent), the convenience (95.8 percent) are the main factors that actively promote blood donation. Conclusion: 53.6 percent of medical staff have "good" knowledge, more than 95 percent are willing to propaganda and support relatives in blood donation. The factors effected to blood donation behavior were save live, good for health, received blood when needed, the movement and convenience.