Veterinarians often are involved in transplantation research projects. They are a fundamental social group who can influence public opinion about organ donation and transplantation (ODT).The objective was to determine the knowledge of Spanish veterinary students about the concept of brain death and the law of presumed consent.A sociologic, multicenter, and observational study was carried out in the veterinary students enrolled in Spain (n = 9000) in a complete academic year. A sample of 2815 students was stratified by geographic area and academic year. The students' attitudes on the psychosocial aspects of ODT were evaluated using a psychosocial validated questionnaire (PCID-DTO Rios). It was self-administered and completed anonymously. Veterinary schools were randomly selected. The questionnaire was applied to each academic year at compulsory sessions.Student t test, χ2 test, and logistic regression analysis were used.The completion rate was 91% (n = 2558). Of students, 66% (n = 1664) understood the concept of brain death, 30% had doubts, whereas 5% believed that a person with brain death can recover and lead a normal life. Concerning legislation, 63% (n = 1615) were against the law of presumed consent, and 37% were in favor. An analysis of variables determining more favorable acceptance of the law showed that year of study (P = .000), knowing a donor (P = .020), and attitude toward ODT (P = .000) did have an effect on acceptance. Most students, 71% (n = 1875), were interested in attending a talk about ODT.Only 37% of Spanish veterinary students would accept the law of presumed consent. Most students were interested in attending an informative talk about ODT.