Abstract Introduction: Depression and cognitive impairment are the most frequent mental disorders in multiple sclerosis (MS) and represent an important cause of morbidity and mortality. The aim of the study was to analyse the main determinants of depression in multiple sclerosis. Materials and methods: Thirty-two patients with relapsing remitting multiple sclerosis (RRMS), treated with Interferon Beta 1a, without relapses and corticosteroid treatment in the last 30 days, were included in the study. The mean age of the patients was 35.4±9.2 years, M/F ratio 0.33. Depression level was evaluated by the Romanian version of Beck Depression Inventory (BDI) and the cognitive function with Paced Auditory Serial Addition Test 3 (PASAT 3), Symbol Digit Modalities Test (SDMT). The functional status and disability level of the patients were evaluated with Multiple Sclerosis Functional Composite and Expanded Disability Status Scale. In all patients a cerebral MRI with intravenous contrast administration was performed using a 1.5T MRI device. Results: Twenty-three patients were free of depression (score 1-10), 4 patients presented mild mood disturbance (score 11-16), 3 borderline clinical depression (score 17-20) and 2 moderate depression (score 21-30). The mean BDI score was 8.71±7.16. BDI score correlated significantly with EDSS (R=0.38, p=0.03), PASAT 3 (R=-0.42, p=0.01), SDMT (R=-0.58, p=0.0007), Timed 25-Foot Walk (R=0.43, p=0.01) and 9-Hole Peg Test (R=0.45, p=0.008). From the EDSS functional scores, significant correlations were found with the urinary score (R=0.4, p=0.01) and sensitive score (R=0.49, p=0.004). BDI score correlated significantly with the total number of T2 lesions (R=0.31, p=0.05) while there was no correlation with the number of active lesions. Conclusions: The main determinants of depression in RRMS patients are the cognitive impairment, the affection of fine hand movements (9-HP), gait impairment (T25FT) and bladder and sensitive dysfunction.