Due to their importance as crop species, solanaceous plants such as tobacco, potato and tomato have been studied in great detail with respect to carbohydrate partitioning using classical physiological methodology. During the last decade, molecular tools have enabled the isolation of many genes involved in carbohydrate metabolism, and the development of efficient transformation technology, especially for the Solanaceae, has allowed the creation of transgenic plants, that are altered by the activity of individual genes. The physiological analysis of these transgenic plants has contributed considerably to our current understanding of how assimilates are produced, mobilized, translocated, and allocated in higher plants. This review aims to cover the current knowledge in the area of molecular genetics of sucrose biosynthesis, transport and utilization in these species.