The vegetables demand is increasing at a greater pace because of the rising world population and changing food preferences. This ever-increasing demand can be fulfilled by increasing crop yield while land and other agricultural resources are already decreasing. In this scenario, heterosis breeding can help to increase crop yield from the same piece of land. The vegetables’ gene banks keep potential genotypes which are sources of male sterility, self-incompatibility, and gynoecism. These mechanisms are critical for the production of hybrid seed on a profitable scale which is otherwise not possible by the conventional methods of hand emasculation and pollination. Using these mechanisms, different systems of hybrid seed production (three-line system, two-line system, and gynoecium line system) have been devised for vegetables. These systems are being used to produce hybrid seeds in tomato, onion, garlic, hot and sweet peppers, cucurbits, and cruciferous vegetables. The cultivation of these hybrid crops has boosted the vegetable production manifolds. This chapter describes the mechanisms and systems of hybrid seed production in vegetable crops. It also explains the standards of seed production and seed certification system of Pakistan.