The production and productivity of major crop plants have reached their plateu during the past decade because of adoption of green revolution technologies. However, further increase in production of cereals with improved cereal quality is imperative to feed the increasing population in spite of shrinking available land due to urbanization and industrialization. Advances in cellular and molecular biology have developed new scientific tools to overcome some of the limitations in crop breeding technologies. Developments of saturated molecular maps of most of the crop species and association of several genes of agronomic importance with DNA markers have increased the confidence of plant breeders for their utilization in crop improvement. However, elucidation of methodologies and directions of applying marker-assisted selection (MAS) in crop breeding programs are still in its infancy. In this paper. we have described the use of appropriate methodologies for major Mendelian genes and polygenes controlling important traits of plants and their successful utilization in crop improvement. These new directions in crop breeding technologies would have an impact on increasing the quantity and quality of crop production.