Introduction: The various problems presented by older people with vulnerability factors can be solved from a preventive approach through education that highlights the positive aspects of aging, which are often minimized due to stereotypes and prejudices associated with age present in society. and that influence the perception of old age and the elderly by professionals and future professionals who care for the elderly. Methodology: Descriptive within-subject study of repeated measures (before and after) to evaluate the impact of the Geriatric Nursing course on undergraduate Nursing students in 2019. The census-type sample was carried out based on the total number of students who were studying the subject, 52 sixth-semester students in Mexico and 68 seventh-semester students in Chile. Data collection was carried out in both countries at the beginning and end of the subject, through an instrument with sociodemographic questions and the CENVE Questionnaire to measure the level of stereotypes associated with old age presented by students. Descriptive and inferential statistics were used, the reliability test of the instrument was also carried out by means of Cronbach's Alpha. To carry out this research, the approval of the Ethics and Research Commissions of the selected educational institutions in both countries was obtained. Results: When comparing the results between Chile and Mexico, a descriptive difference was observed between Mexico (x = 40.76) and Chile (x = 34.62) in the evaluation at the beginning of the subject and in the post-intervention measurement, in Mexican students (x = 41.04, SD = 5.90) and Chileans (x = 30.09; SD = 7.05), the Mexican students presented “high negative stereotypes” and the Chilean students “low stereotypes” according to the cut-off points of the instrument. The two-way ANOVA test showed a statistically significant interaction between Nation/Time (F = 6.439, p = .012), showing that Chile has greater positive effects in its course to reduce negative stereotypes in nursing students than Mexico. Conclusions: The positive effect of teaching the subject of Geriatric nursing in the training of future nursing professionals was empirically verified, being an effective intervention to reduce negative stereotypes about aging, old age, and the elderly.