This prospective study aimed to evaluate the relationship between serum ischaemia-modified albumin levels and Bell's palsy severity.The study included 30 patients diagnosed with Bell's palsy and 30 healthy individuals. The patients were separated into three disease severity groups (grades 2, 3 and 4) according to House-Brackmann classification. Blood samples were collected from all participants and the results compared between groups.Significant differences in serum ischaemia-modified albumin were found between the study and control groups (p < 0.001); values were significantly higher in the study group than in the control group.The significantly higher levels of serum ischaemia-modified albumin in the study group suggest that Bell's palsy pathogenesis is associated with oxidative stress.