The use of combination pesticide (profenofos 40% + cypermethrin 4% EC) is on the rise in India and elsewhere. Cypermethrin is reported to be a tumor promoter, but its tumor-promoting potential along with profenofos is yet to be studied. A short-term, in vivo test for detection of a tumor promoter is cost-effective, saves time, and requires fewer animals than conventional methods. We report on a short-term test based on mechanisms of significant importance in tumor promotion. In this study, we have tested the tumor-promoting potential of a combination pesticide containing profenofos 40% and cypermethrin 4% EC in Wistar rats. Although cypermethrin has been reported as a tumor promoter, our study shows that the combination pesticide containing profenofos 40% and cypermethrin 4% EC is not a tumor promoter.