Currently, there is a continuous and growing concern about the food we daily eat, mainly the vegetables. Vegetables are packed of phytochemicals, minerals and vitamins due to which their role for health is significant.Antioxidant compounds such as polyphenolics play an essential part to scavenge the free radicals and inhibit the oxidative mechanism, which is responsible for degenerative health disorders. Allium cepa L. (onion/Piyaz) is an important vegetable crop, which is cultivated through the world mainly in Asia. It is one of the best nutritive sources of biologically active compounds. Many epidemiological studies have revealed that ingestion of A. cepa decreases the risk of cancer, cardiovascular diseases and neurodegenerative disorders. Furthermore, A. cepa possess antioxidant,anti-inflammatory, antimicrobial properties, which are mainly accredited to abundant contents of phytochemicals such as flavonoids, phenolic acids, organosulphur compounds, thiosulfinates, anthocyanins, vitamins and minerals (Fe, Se, K, I, S etc.). It is well established that climate, growing conditions, soil composition, post-harvest condition and genetic diversity effect significantly on the production of secondary metabolites or phytochemicals and properties in plant species related to active constituents. In Pakistan, A. cepa is cultivated under diverse agro-ecological conditions. However, impact of environmental conditions on secondary metabolites production and their properties has seldom been described. In this perspective, current study is designed to investigate the impact of environmental factors and genotypic difference on the phytochemical composition, in vitro antioxidant capacity and antimicrobial properties of A. cepa cultivated under diverse agro-climatic conditions in Pakistan. Proposed study will be helpful in understanding, impact of environmental conditions i.e. temperature, precipitation, altitude and genetic diversity on secondary metabolites or phytochemicals production and their activity in plant species, particularly in A. cepa. Furthermore, proposed study will be valuable for consumers, environmentalists, farmers and plant breeders to select the super varieties of A. cepa having maximum yield and significant contribution in health along with best growing conditions.