Grain yield is the most complex quantitative trait of intensive invetigation but remains poorly understood genetically.In this review paper,the published results on the genetic dissection of rice yield potential by QTL appoach were critically reviewed.During the past 15 years,large numbers of QTLs affeting grain yield and its components in rice have been identified mostly using random segregating populations.Most QTL studies have been focused on identification and cloning of single main-effect QTLs,even though there is strong evidence that epistasis plays an important role in determining variation of grain yield and its components.While there is no doubt that QTLs are real genes with specific functions,results from these QTL studies do not seem to provide sufficient knowledge linking the underlying genes and the complex phenotype,nor provide sufficient information for breeders to improve grain yield by marker assisted selection.Finally,the authors believe that the future studies should be directed to identification of QTL networks underlying complex traits and to integration of QTL discovery with trait improvement.