Treatment of wounds and burn injuries is very important. Nowadays, the tendency to research complementary medicine has increased. In this clinical trial, 60 patients hospitalized in the burn ward who met the inclusion criteria were randomly assigned to two groups: intervention (n = 30) and control (n = 30). In addition to treatments, the intervention group received one capsule (2 g) of Calendula officinalis daily, for two weeks, and the control group received the placebo. Wound status was assessed with the Bates-Jensen Wound Assessment Tool (BWAT) on the 1st, 7th, and 15th days of the study in both groups. The mean total score of wound status using BWAT at the 1st, 7th, and 14th days in the intervention group was 48.23, 35.93, and 22.97, respectively, and in the control group was 48.90, 42.57, and 37.8. Statistically, wound condition on the first day was at the same level for both groups. Wound healing scores in the two groups increased during the 1st to 15th days of the study (P <0.001). However, in the intervention group, the range of wound healing changed on days seven and 15 and was greater than in the control group. Based on the results of this study, C. officinalis may have beneficial healing properties and be effective in accelerating the healing of second-degree burn wounds and can be used as a supplement to treat wounds.