[en] Constraints of conventional cross breeding in fruit trees, wide market acceptance of definite cultivars, especially in apple, pear, citrus and wine grape, and the increased impact of natural mutants provide incentives for mutation breeding. Only few induced mutants in fruit trees have been commercialized and are being planted on a large scale. The main method followed in mutation breeding of tree fruit has been acute irradiation of meristematic multicellular buds but, Chimera formation and reversion present a serious problem. 87 refs, 4 tabs