Introduction: Teachers, by creating a culture of health within their classrooms, are agents of change and have an important role during students’ formative years. This study aimed to investigate the effect of an educational intervention on the nutrition literacy of primary school teachers in Yasuj. Methods: In this quasiexperimental study, 110 primary school teachers in Yasuj, who were randomly selected from two areas of the city (intervention and comparison groups), were included in the study. Nutrition literacy was measured by using a validated tool for the Iranian society. After analysing the data, the educational content and structure were developed to improve nutrition literacy. The intervention consisted of two training sessions, provision of educational pamphlets and sending of two SMS messages. Data were analysed before and three months after the intervention by using SPSS16 software. Results: Before the intervention, the mean ± standard deviation of nutrition literacy in the comparison and intervention groups were 27.04±3.15 and 27.25±3.27, respectively. According to repeated measures ANOVA, nutrition literacy score improved significantly three months after the intervention (p time = 0.001). Besides, there was a significant difference between the two groups (p group = 0.03). The interaction between time and group was also significant (p time × group = 0.001). Conclusion: The educational intervention led to an improvement in the nutrition literacy of primary school teachers in Yasuj.