The development of transgenic plants strongly depends on the stable introduction of foreign nucleic acid into the plant genome. Recently, various transformation methods have been developed and successfully used for the development of transgenic plants of agricultural importance. Various vectors have been prepared, however the binary vector based on agrobacterial T-DNA is most commonly used. Of vectorless gene transfer systems, particle bombardment seems to be most useful. In both approaches, stable integration of DNA is based on random hybridization. The transformation efficiency is measured by the level of transgene expression and it may be potentially improved by different modifications, including insertion of multiple copies of promoter into a particular gene, insertion of procaryotic enhancer, increasing of mRNA stability, insertion of SAR/MAR sequences at the ends of gene, etc. Very recently it has been found that the increase of histone synthesis enhances transgene expression possibly as a result of increased transformation efficiency. Transgenic plants production also depends on the efficiency of the plant regeneration system which is used. There is no universally applicable method for regeneration of different tissues from various sources, thus regeneration protocol should be modified appropriately for each tissue and species.