The mobile blood collection at specific sites after the promotion of this activity is a way of obtaining voluntary donations and an effective way of recruitment of loyal donors. An opinion survey-type instrument to measure the quality of care to blood donors who go to mobile blood collection activities was presented. This instrument took into account several service attributes; it was validated on the basis of expert criteria and pilot tests. It was applied to donors seen in mobile blood collection activities that are carried out by the Regional Productive Center of Blood in Maule, Chile. From the analysis of the various dimensions, the personal treatment was the best evaluated one. Similarly, professional competency was the second best evaluated. Having one validated instrument in place allows determining the levels of quality of care, knowing the problems to be followed-up, suggesting actions for improvement and evaluating their evolution. The above-mentioned is aimed at having loyal donors.