BACKGROUND: Children are often exposed to ergonomic risk factors at school. Thus, the school is a potential environment for developing musculoskeletal disorders and implementing back care programs. OBJECTIVES: To evaluate the effect of an educational program on schoolchildren's knowledge regarding back pain prevention. METHODS: 392 students from 4th to 8th grade from a Brazilian state school took part in the study; 114 students (30%) were evaluated at follow-up. The back care program included pre- and post-intervention assessments and a follow-up assessment, as well as theoretical and practical lessons. The time interval between the pre- and post-intervention assessments was 9 weeks, and between the post-intervention and follow-up assessments, it was 2 years. Statistical analysis included non-parametric ANOVA tests. Significance level was set at 5% (p<0.05). RESULTS: There was a significant increase (p<0.001) between pre- (3.6±2.9) and postintervention (7.5±2.2) scores and a significant decrease in the follow-up score (5.1±2.5). However, the follow-up score was still significantly higher (p<0.001) than the pre-intervention score. The rate of correct answers in the post-intervention assessment increased for all questions, and some of them were still high at follow-up. Significant differences were identified for the comparison between grades, with the 8th grade being significantly different from the other grades. CONCLUSION: The back care program showed an increase in the level of knowledge of Brazilian schoolchildren. Two years after the intervention, students still retained ergonomic concepts. Although the program has limitations, theoretical knowledge acquisition is the first step towards adopting healthy postural habits to prevent back pain.