Like many chronic illnesses, Behçet's disease (BD) has been reported to negatively affect the quality of life and mental health of the individuals diagnosed with this disease. This study aims to investigate the relationship between disease activity and depression and sleep quality in BD. Forty patients with BD and 30 healthy subjects (controls), aged 18-65, were included in this study, and all of the subjects enrolled in this study were assessed in terms of depression and sleep quality using the Beck depression index (BDI) and Pittsburg sleep quality index (PSQI). Additionally, the subjects with BD were also assessed using the Behçet's disease current activity form (BDCAF). It was determined that the depression and sleep quality scores were significantly higher in the BD group compared to those in the control group (p = 0.012 and p = 0.020, respectively), and in the BD group, significant positive correlations were determined between the BDCAF and depression and sleep quality scores (r = 0.559, p < 0.001 and r = 0.462, p = 0.003, respectively). We believe that the assessment of BD patients for depressive symptoms and sleep quality, and providing medical support to those who need it, will contribute to the treatment and follow-up processes of BD.