Background: Cognitive impairment is one of the most crucial disorders among multiple sclerosis (MS) patients. Since MS is an inflammatory disease and Boswellia papyrifera has anti-inflammatory effects, the influence of B. papyrifera on cognitive impairment in MS patients has been investigated in the present study.Methods: In this clinical trial, 80 MS patients who referred to the clinic of Shafa Hospital, Kerman, Iran were selected. Having completed a written consent form, patients with relapsing remitting MS, with no occurrence of a new attack throughout 1 month before the study, with no pregnancy or breastfeeding entered the study. The patients were randomly divided into two groups; then Brief International Cognitive Assessment for MS (BICAMS) test was carried out. One group received B. papyrifera (capsule 300 mg, twice a day) while the other group received placebo with the same dose for 2 months. After 2 months of treatment, BICAMS was redone and changes were analyze .The significant change value on the before-after BICAMS points were considered to be 8, 13, and 7 points for the symbol digit modality test (SDMT), the California verbal learning test (CVLT), and the brief visual-spatial memory test revised (BVMT-R), respectively.Results: The patients’ mean age was 36.58 8.50 years. The mean duration of disease was 7.41 4.13 years. About 84.2% (n = 64) of the patients was female. In the BVMT-R, 13 patients (34.2%), who had already taken B. papyrifera, were shown to have significant improvement compared to the placebo group with no improvement (P < 0. 001). About 12 and 8 patients in the treatment and placebo groups in the SDMT, respectively (P = 0.200) and 17 and 12 patients in the treatment and placebo groups in the CVLT, respectively (P = 0.170) had signi@cant change values.Conclusion: B. papyrifera showed significant improvement in visuospatial memory, but had no effect on verbal memory and information processing speed.