The effect of Amiprophose methyl (APM) on mitotic cells of the root meristems of Allium cepa was studied at a range of concentrations (4-6 μmol/L), length of treatments (4-16 h). The results showed that the mitosis metaphase index (Met. I ) could be obviously improved from 0.8 (in control) to 5.0 or 5.2 respectively when the root meristems were treated with APM at a range of concentrations 5-6 μmol/L for 16 h. The result also indicated that APM treatment (more than 4 μmol/L) severely affected the cell ...