Oral lichen planus (OLP) is a common inflammatory disease with unknown etiology. Depression, stress and anxiety are psychological factors that their influence on the expression of lichen planus by affecting the immune system's function has been confirmed. There is a probable relationship between anger and OLP expression. Therefore, the present study aimed to evaluate the association of "anger" and OLP. In this descriptive study 95 subjects were included in 3 groups. A: patients with oral lichen planus, B: positive control, C: negative control. Anger and its indices were assessed by the State-Trait Anger Expression Inventory-2 (STAXI-2) questionnaire, and pain was measured via the Visual Analogue Scale (VAS). The collected data were analyzed statistically using SPSS 18 software. The lichen planus and positive control groups bore higher total anger index (AX index) values compared with the negative control. Comparing anger expression-in (AXI) among the lichen planus and negative control groups revealed higher grades in lichen planus group. Evaluating the pain severity index (VAS) data and anger indices in lichen planus group, Spearman's Rank Correlation Test revealed a significant correlation between TAngR (reactional anger traits) and pain severity. The findings of this study indicated that there was a significant correlation between anger control and suppression of lichen planus development. On the other hand, the patients with more severe pain mostly expressed their anger physically. Based on the findings, we can make the claim that anger suppression and its control-in (gathering tension) may play a role in the development of lichen planus as a known psychosomatic disorders.