Background and Objectives: Oral submucous fibrosis (OSF) is a chronic condition of the oral cavity which results in permanent disability. A number of studies have proven that the management of premalignant diseases should include antioxidants. Therefore, a study was carried out to evaluate the efficacy of spirulina as an antioxidant adjuvant to corticosteroid injections in the management of 40 oral submucous fibrosis subjects of south Karnataka and north Kerala. Materials and Methods: An intervention study was conducted on 40 oral submucous fibrosis cases, 40 patients were divided into two groups, group A (spirulina group) and group B (placebo group). Group A received spirulina 500 mg twice daily and biweekly intralesional steroid injection of Betamethasone 4 mg/ml for 3 months and group B was given placebo capsules twice daily and biweekly intralesional steroid injection of Betamethasone 4 mg/ml for 3 months. The results were analyzed with the paired " t" test and the unpaired " t" test. Results: Clinical improvements in mouth opening was significant in the posttreatment period in both Spirulina and placebo groups. Both the groups showed statistically significant reduction in burning sensation. However, when both groups were compared, mouth opening and burning sensation was found to be statistically very highly significant in favor of the spirulina group. Conclusion: Spirulina can bring about clinical improvements in OSF patients. The observed effects suggest that spirulina can be used as an adjuvant therapy in the initial management of OSF patients. However, studies involving larger samples and longer period of treatment follow up are suggested in the future.