The study aimed to investigate the effects of surface treatments, including plasma, on the peel bond strength between two maxillofacial silicones and two resins with and without thermocycling. Forty-eight experimental groups (n=10) were generated incorporating the two different resins (auto-polymerizing acrylic resin and light-curing urethane dimethacrylate resin [AR and LR, respectively]), two different silicones (M511 and Z004), aging (thermocycled/no thermocycling), and six different surface treatments, including polishing, grinding, polishing+argon plasma, polishing+oxygen plasma, grinding+argon plasma, and grinding+oxygen plasma. Surface topography of a specimen from each surface treatment group was examined by atomic force microscopy. After surface treatments, silicones were polymerized. The peel bond strength values of the control and thermocycled groups were determined. Atomic force microscopy showed that surface topographies of the ground specimens were irregular. Polished specimens showed higher peel bond strength than ground specimens. Plasma application appeared to have improved the bond strength between the resins and silicones.