Major depression belongs to mood disorders and characterized by worthlessness, no interest or happiness in any activity; lasting for atleast two weeks. Etio-pathological changes of major depression include oxidative stress leading to free radical synthesis which causes damage to carbohydrates, proteins, lipids and nucleic acids. Nucleic acid damage can be identified by either single or double strand breaks and for quantitative estimation of the same, neutral or alkaline comet assay is performed. Fluoxetine is the drug of choice for treatment of major depression having antioxidant function. In the current study eighty drug naïve major depression patients were recruited and comet parameters namely total comet length, head diameter and tail length were measured before starting the treatment and after completion of eight week fluoxetine therapy. The levels of comet parameters were higher in females than males suggesting higher prevalence of major depression among females. On categorizing into three age groups, the numbers of major depression patients belonging to 18–30 year age group were higher than 31–40 and 41–50 year age groups. All the parameters of deoxyribonucleic acid damage were reduced after eight week of fluoxetine therapy indicating that fluoxetine has anti-oxidant action along with its antidepressant properties, which cause reversal of oxidative stress induced damage occurring during major depression.