Background: Burning is one of the worst accidents that people may now experience in modern society. One of the most critical problems of burn patients is the anxiety caused by medical treatments such as burn dressing. The present study aimed to determine the effect of rhythmic breathing on the anxiety of dressing change in burn patients. Materials and Methods: This experimental clinical trial was done on 60 burn hospitalized patients in Ayatollah Mousavi educational-therapeutic hospital of Zanjan province in 2017. The sampling was performed continuously and the samples were randomly assigned to control and experimental groups (30 subjects in each group). The data collection tool included a demographic questionnaire and numerical anxiety scale. First, the demographic characteristics questionnaire was completed by the samples. Then, the rhythmic breathing was taught to the experimental group for 20 minutes until complete learning, and they were asked to perform the rhythmic breathing during dressing. Before and after dressing, anxiety was evaluated in the experimental and control groups for 3 consecutive days. After collecting data and entering them into SPSS 20, data were analyzed using descriptive statistics, chi-square test, independent and dependent t test, and Friedman test. Results: Based on the findings of the study, both groups were homogeneous in terms of age, gender, education, percentage and the degree of burn, and there was no statistically significant difference. The results of the Friedman test showed that the anxiety severity had a statistically significant difference in both control and experimental groups before and after the intervention (P<0.001). However, the severity of anxiety after the intervention further reduced in the experimental group compared to the control group, and this reduction was statistically significant in the experimental group (P<0.001). Conclusion: In general, rhythmic breathing is effective in reducing anxiety caused by a dressing change in burn patients. Thus, this method can be used to decrease the anxiety of dressing.