Cytological investigations have been carried out in the experimental set of individual treatment of chemical mutagen such as EMS concentration in Pea (Pisum sativum L.). Seeds of Pea were subjected to different concentrations of EMS. The treated root tips showed varying degree of mitotic abnormalities almost in all the concentrations of EMS. The frequency of mitotic abnormalities was found to be more in highest concentrations of EMS. The various types of mitotic aberrations such as fragments, bridges, laggards, micronuclei, early and late separation were scored in case of root meristem cells of treated materials. Taking the percentage of mitotic aberrations and germination as an index of effectiveness of a mutagen concentration proved to be the most effective.