This study investigates the effect of smokeless tobacco on the tribological properties of two commercially used dental composite materials: Tetric N-Ceram and Z350 Dentin shade. It is to evaluate the effect of smokeless tobacco on the wear properties of two dental composite materials after some stipulated period. The wear test was conducted on pin-on-disk tribometer in the presence of artificial saliva under different loading conditions of 10, 15 and 20 N. The pins of the dental composite material were immersed in tobacco solution. The tribological behavior was studied after 2 days, 3.5 days, 6 days, 15 days and 1 month which represented the real conditions for the contact of 1 week, 2 weeks, 1 month, 2 months and 5 months, respectively, between the dental material and the tobacco solution. Under different loading conditions, Z350 Dentin material exhibited much less wear than the Tetric N-Ceram material in the presence of synthetic saliva for the specimen with or without tobacco immersion. The microstructure of the pin surface was inspected using scanning electron microscopy. © IMechE 2020.