Background: Oral lichen planus (OLP) is a common inflammatory disease of unknown origins. Recent studies have considered nutritional factors concerning the pathogenesis of many autoimmune disorders. The objective of the present study was to investigate the plasma levels of magnesium (Mg), calcium (Ca), zinc (Zn), copper (Cu), and iron (Fe) in this disorder. Methods: Included in this observational case-control study was 40 patients with OLP and 40 age and sex matched healthy control subjects. Plasma levels of Mg, Ca, Zn, Cu, and Fe were specified using an autoanalizer. Results: The serum level of Ca was higher, but Mg, Cu, Fe and Zn serum concentration did not differ significantly between the patients with OLP and the healthy controls. Mean Zn concentration was lower in patients with erosive lichen planus compared to the non-erosive group and the healthy controls. However, only the difference between erosive lichen planus patients and healthy participants was significant. The mean Zn level was lower than the normal range (70 µg/dl) in both the cases and controls. The concentration of Fe was significantly higher in men male patients than in females; however, the difference between men and women was not significant in the healthy control group. The mean Cu/Zn ratios in erosive and patient groups were slightly higher compared with the controls. Conclusion: Trace elements such as Ca may play a role in the ethiopathogenesis of OLP. Nevertheless, other elements such as Zn or Cu may influence OLP, which requires further evaluation on larger samples.