Purpose: The purpose of this study is to evaluate the results of patients, with a chief complaint of recurrent aphthous stomatitis (RAS), who were found to have zinc deficiency as the predisposing factor and received appropriate replacement therapy. Materials and Methods: A retrospective study was conducted using data from the medical records of patients with a chief complaint of RAS. Patients with potential ulcer-causing conditions were excluded. All patients were intraorally examined to rule out trauma-associated aetiologies. Blood tests were ordered to measure total blood count, serum transferrin, ferritin, zinc, folic acid and vitamin B12 levels. Results: A total of 48 patients, 34 with zinc deficiency and 14 with both zinc and iron deficiencies, were included in this study. Patients received an initial three-monthly replacement treatment and blood tests for the certain deficiencies were repeated at the end of this time interval. Two patients with zinc deficiency reported no relief due to incorrect intake of tablets with milk. Following correct instructions, all patients reached normal serum mineral levels and reported no recurrences. All patients remained asymptomatic and their mineral levels were monitored in every 3 months to detect any abnormalities. Overall mean follow-up for this study was 12.06 months (range: 8-28 months, SD: ± 5.7). Conclusion: Zinc deficiency should be considered and investigated as part of the diagnostic process of RAS. A simple blood test may aid in correct diagnosis and complete resolution of this recurring condition rather than constant prescription of certain medicines to suppress the symptoms. Keywords: diet, phytate, oral ulcers, recurrent aphthous stomatitis, zinc deficiency