Manganese, a metal of the first group of transitional element is essential for nutrition in higher organisms (Joardar et al. 1988, WHO 1981). The metal has been found to be the least toxic of essential elements though excess leads to poisoning and different degrees of damage to the exposed organs (Venugopal and Luckey 1978). Manganese toxicity is one of the most important factor causing growth limitation in acid soils (Foy 1983, 1984) and in its different forms it is also a clastogenic and cytotoxic for higher organisms (Joardar 1988, Shukla and Singhal 1984, WHO 1981). Information on the effects of Mn on cell division and chromosomes is relatively meagre. In the present study two different plant systems and one mammalian system were used for evaluation of the cytotoxicity and clastogenicity of the trace element, manganese. © 1990, Japan Mendel Society, International Society of Cytology. All rights reserved.