Objectives: Psychiatric disorders including somatization impact pain severity and chronicity. This study aimed to determine sleep quality and the presence of psychiatric disorders in patients with chronic lateral epicondylitis (LE) and to investigate the effect of these comorbidities on pain levels. Methods: This study included 46 patients diagnosed with chronic LE and 46 healthy controls. Visual analog scale (VAS) was used for the assessment of pain intensity. The prevalence of depression and other psychological factors was examined using Beck Depression Inventory (BDI) and the Symptom Checklist-90-Revised test (SCL-90-R). Pittsburgh Sleep Quality Index (PSQI) was used to evaluate sleep quality. Results: The mean BDI (p<0.001), all subdivisions of SCL-90-R including somatization (p<0.001), and the mean global PSQI scores (p=0.002) were found to be significantly higher in patients with chronic LE than those in the control group. The presence of depression according to BDI was 41.3% in the patient group. About 60.8% of the patients had somatization and 71.7% had poor sleep quality. VAS scores were significantly higher in the patients with depression, somatization, and low sleep quality indicating a low positive linear relationship (r=0.357, r=0.360, and r=0.463, respectively, and all p<0.05). Conclusion: Psychiatric disorders and poor sleep quality are frequently observed in patients with chronic LE. These comorbidities negatively affect pain levels and may be linked to pain chronicity. Therefore, the potential coexistence of psychiatric disorders should be kept in mind when determining the treatment protocols for patients with chronic LE and adjunctive treatment should be given if necessary.