Zea mays is an important cash crop grown for food and feed throughout the world. The growth, yield and quality of corn grain and fodder are highly affected by various biotic and abiotic factors that caused reduction in output. The crop yield and quality may be improved through conventional breeding by selecting genotypes on the basis of genetic variability. Various statistical analysis and designs like randomized complete design, randomized complete block design, factor factorial analysis, combining ability analysis, heterosis, heterobeltiosis, additive, dominance and gene interactions helped plant breeders to identified best inbred lines, synthetic varieties and hybrids. The traits that are under polygenic control may be improved through quantitative genetics and quantitative plant breeding approaches. The non-conventional or advanced molecular plant breeding now a day helping in improving the potential of crop plant by inducing gene (s) of interest in crop plants. Biotechnology also helped to develop biotic and abiotic resistant crop genotypes. In present review, the role of conventional and non-conventional breeding has been explained for better understanding of breeders to work with conventional and molecular plant breeding. [Fawad A, Muhammad A, Kanwal N Ali Q, Niazi NK. Crop improvement through conventional and non-conventional breeding approaches for grain yield and quality traits in. Life Sci J 2015;12(4s):38-50]. (ISSN:1097-8135). http://www.lifesciencesite.com. 6