The objective of this study was to explore the mutagenic and cytotoxic effects of Napoleon 4EC pesticide used in Turkey to control insect pest by using two standard assays. The Allium cepa test was used for determined the cytotoxic effects of this pesticide. For this test, onion seeds were exposed to Napoleon 4EC (100, 200, and 400 ppm) for 24, 48, and 72 hours. For each test group root tip cells were stained with Feulgen and five slides were prepared for each concentration and counted microscopically. The concentrations Napoleon 4EC was compared with the value for the negative control using Dunnet-t test, 2 sided. The results indicated that mitotic index was clearly decreased with increasing the concentration of Napoleon 4EC in each treatment group as compared to the controls. The percentage of mitotic phases has been markedly impacted. Five different doses of the pesticide (50, 100, 200, 400, 800 μg/plate) were examined with Ames test using Salmonella typhimurium strains TA98 and TA100 with and without S9 metabolic activation for mutagenic activity. Ames test results showed a dose dependent effect, but not twice the negative control for S. typhimurium TA98 and TA100, with or without S9 mix except 800 μg/plate doses. In 800 μg/plate doses, colony numbers are two-fold increase according to colony number of control group. So, this places the this compound as a weak mutagen according to the parameters.