The monograph summarizes the theoretical information on mutagenesis, the use of this method in the breeding of agricultural plants and the results achieved. The results of the authors' long-term research on the creation of initial breeding material based on chemical mutagenesis in the breeding of fruit and berry plants: black and red currants, gooseberry, felt-cherry and sweet cherry trees are presented. The monograph is addressed to researchers, breeders, graduate students, undergraduates, teachers and students of agricultural universities, specialists of horticultural farms and amateur gardeners.