Abstract: Heterosis is manifested as improved performance for F1 hybrids generated by crossing two inbred parents. The selection of parents for effective hybridization depends on the nature and magnitude of heterosis over mid parent, heterobeltiosis and economic heterosis present in genetic stocks. The response of heterosis either positive or negative mainly depends on the breeding objectives and the type of the crops used. In cereal and vegetable, positive and negative heterosis desired for yield and maturity. Moreover, the nature of pollination, the floral biology and the natural out crossing rate of in cereal and vegetable crops is important for heterosis. In some self pollinated vegetable crops (egg plant), heterosis became very large, with hybrid yield advantage ranges from 33-97%, due to, flowers are perfect and normally the natural out crossing rate near zero. However, most of these crops, produce few seeds per cross make it difficult to produce hybrids economically. Most cereal crops are cross pollinated, however, the natural out crossing rate of 25% and heterosis yield of 28-47%. Nevertheless, self incompatible inbred lines are common in some cross pollinated vegetable and inbreeds can be self pollinated by bud pollination. In vegetable crops, heterosis developed in to four ways, self pollinated with few seed per cross, self pollinated with many seed per cross, cross pollinated with little out crossing and cross pollinated with much out crossing. Exploitation of heterosis in cereal and vegetable provides enhancing food security and represents a greatest applied achievement in the discipline of plant breeding.