Purpose. The purpose of this research is exploring the role of altruism, moral norm, donor's knowledge, and perceived risk in influencing the willingness of people in donating blood.
Design/methodology/approach. Data is collected through survey that is guided by questionnaire. Data consists of 200 people who has intention to donate blood at Surakarta. Structural equation modeling is an approach used to examine the hypothesis.
Findings. The results found that altruism, moral norm, donor's knowledge and perceived risk were variables considered important by the people in influencing the intention to donat blood. While altruism and donor's knowledge were found no relationship with the perceived risk.
Implication. Findings give some recommendation to Indonesian Red Cross how to get the blood donors effectively. Implications for further research are also recommended in order to get the wider generalization.

Keywords:  Blood Donor's  Intention,  Altruism,  Donor's  Knowledge,  Social Marketing.