Proceedings of a symposium organized by the IAEA and FAO, Vienna, 19–23 August 1985. The symposium examined the usefulness for plant breeding purposes of somaclonal variation, i.e. the occurrence of mutations during in vitro culture with or without the application of ionizing radiation or other mutagens. Another issue was finding ways and means of maintaining the genetic integrity of plants under in vitro conditions, such integrity being of vital importance if in vitro techniques are to be used to propagate virus-free clones of economically important plants, or to preserve germplasm in gene banks. In vitro culture techniques considerably accelerate the plant breeding cycle. This factor and the advantage of using haploids derived from another culture were also discussed at the symposium. Contents: Genetic variation from in vitro culture; Genetic stability of in vitro cultures; In vitro culture with application of mutagens; Haploids; In vitro mutant selection; Use of genetic variation derived by in vitro culture; In vitro techniques as aids in mutation breeding; Genetic engineering.