AbstractPossibilities of using genetic manipulation to improve the effectiveness of mycoherbicides are discussed. Particular emphasis is given to fungal genes involved in the production of specialised structures essential for colonisation and reproduction in pathogenesis and in regulating pathogen specificity. Example are given of relevant genetic transformations in fungi which have already been achieved. In the short term, manipulation of genes encoding for specific enzymes or toxins is considered to be the most promising approach for improving mycoherbicide performance.