Doubled haploids are nowadays a routine part of the breeding programmes and the fastest way to get complete homozygote breeding material. Breeding programmes require large numbers of genetically stable plants. If a sufficient quantity of dihaploid plants are to be produced for use in breeding, the efficiency of in vitro techniques must be continuously improved. The main results we achived in in vitro androgenesis and gynogenesis as follows. In anthera cultures of paprika and eggplants the inclusion of maltose in the induction medium improved the induction of microspore embryogenesis and rised the number of regenerant plants. An efficient, reproducible and economic method was elaborated for the in vitro genome duplication of paprika and eggplants haploids. In in vitro flower-bud and ovary cultures of onion on the basis of our results it could be concluded that application of thidiazuron not only improved embryo induction but increased in the ratio of spontaneous doubled haploids. In case of cucumber and zucchini a reproducible, novel method was elaborated for the induction of in vitro gynogenesis.