Artificial microRNAs (amiRNAs) have been shown to facilitate efficient gene silencing with high specificity to the intended target gene(s). For the plant breeder, gene silencing by artificial miRNAs will certainly accelerate gene discovery, because it allows targeting of all genes in a mapping interval, independent of the genetic background. In addition, beneficial knockout phenotypes can easily be transferred between varieties and across incompatibility barriers. This chapter describes the generation and application of amiRNAs as a gene silencing tool in rice.