RNAi technology is based on a natural process of RNA-directed gene regulation. The technique is widely used for gene functional analysis and to obtain plants with modified traits. The main advantage of this system, particularly when applied for polyploid species, is the possibility of simultaneous silencing of homologous, homoeologous or orthologous genes. The article discusses the results of relatively few papers where RNAi has been used for functional analysis of native genes of wheat and barley. The main part of the article presents the research on RNAi based gene silencing in cereals performed by our group. The experimental basis of our work was the elaboration of efficient Agrobacterium-based transformation and plant regeneration systems of different cereal species (wheat, barley, triticale and oat). Currently, the method is applied for modification of two types of traits in wheat, triticale and barley. The first one is a technological trait related to cereal grain hardness. It is genetically controlled by Pina and Pinb genes. We obtained over a hundred transgenic lines with various degrees of Pina and Pinb silencing. Currently, the lines are being analyzed for the amount of PINA and PINB proteins, composition of storage proteins, and the grain texture. The second set of traits depends on CKX genes encoding cytokinin oxidase/dehydrogenase ? the part of the system specifically governing the cytokinin level in different organs and developmental stages. We obtained over forty barley transgenic lines with silenced HvCKX1. This modification was found to be tightly correlated with enhanced plant productivity measured as the higher grain number and higher mass of a thousand kernels. The T1 and T2 transgenic seedlings developed bigger root system.