Objective: Recurrent aphthous stomatitis (RAS) is the most commonly seen inflammatory disease in the oral mucosa affecting 5%-25% of the general population. The etiology of RAS is still not fully understood and its treatment is very challenging. With its anti-inflammatory affects, colchicine is used for systematic treatment of RAS. In this study, we want to examine the effects of colchicine on platelet density, mean platelet volume (MPV), neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and red cell distribution width (RDW) of the patients with RAS. Methods: Fifteen male and 45 female RAS patients that were taking colchicine were investigated retrospectively. The whole blood parameters of the patients were observed before starting colchicine treatment and in the third month of colchicine treatment. Results: Significant decrease in the levels of NLR, white blood cell count and RDW of the RAS patients under colchicine treatment was observed. Moreover, no changes were seen on MPVs, PLRs and hemoglobin (Hb) levels. Conclusion: It was determined that colchicine lowers the levels of NLR, white blood cell count and RDW. Furthermore, no changes were seen on MPVs, PLRs and Hb levels.