Background:Depression is a medical condition, illness of the brain in which an individual is conquered by the feeling of sadness, hopelessness, guilt and so on. Depression is one of the commonest human blight, mental illness causing more ‘years lost to disability’ (YLD) than any other illness and the sufferer learns to live with it, adapts it both mentally and physically. WHO fact sheets states that depression affects nearly 350 million people; yet, difficult to recognise initially, then diagnose and ultimately treat. Since the disease creates disinterest in day-to-day activities, it also affects dietary pattern of the person, leading to inadequate, imbalanced diet essential for maintaining mental health. B Complex vitamins; pyridoxal phosphate, folate and cobalamin plays an important role in maintaining good physical and mental health as these act as co-enzymes and co-factors in metabolic processes. Biosynthesis of GABA, the inhibitory neurotransmitter of the brain requires PLP. Aim and Objective: Estimateserum levels of vitamin B6, B9, B12along with GABA, TSH and total cholesterol in controls and the cases. To evaluate the association of study biochemical variables with disease severity