Objective. The aim of this study was to analyse the hematologic status if Thai patients with oral lichen planus (OLP), recurrent aphthous ulceration (RAU) and stomatitis or glossitis (ST/GT). Study design. Sixty one patients were examined consecutively for hematological abnormalities including serum folate, red cell folate and serum vitamin B[subscribe12] levels. The patient were divide into 3 major groups with OLP(22), RAU(19) and ST/GT(20). Result. Low red cell folate and low serum with red cell folate were found in patients with OLP (11/22) , RAU(11/99) and ST/GT(8/20). However, there was no statistically significant difference in folate deficiencies among these groups (P.0.05). Low serum vitamin B[subscribe12] levels were found in only 5 of 61 cases. Gastrointestinal disorders were found in 15 of all these groups. Treatment in patients with deficiencies showed good response in approximately 46.3% of the cases. Conclusion. Investigations for folate and vitamin B[subscribe12] levels are recommended in patients with refractory oral lesions for the benefit of treatment.