The aim of the study was to develop and evaluate the impact of an educational intervention with the use of text messages (SMS) in a first aid course. A prospective study and intervention was conducted. Two steps were implemented: 1) a qualitative study to design the SMS and 2) the intervention with the sending of the SMS messages. The outcome variable was the final grade of students. Multivariate models were constructed, prevalence ratios and confidence intervals at 95% were calculated. The first phase revealed that the SMS should be educational-theoretical, motivational, and multiple choice. In the intervention there were 66 participants in the control and intervention group. The average age was 17.7 (± 1.2) years. The intervention group obtained higher scores compared with the control group (PR = 4.82; 95% CI: 1.58 to 14.72). In conclusion, SMS with informative and motivational content is useful in the formation of undergraduate medicine.