Purpose: The purpose of this study was twofold: (1) to estimate the level of microbial contamination found on commercial guides (CG) and in-house laboratory guides (LG) prior to use, and (2) to evaluate the antimicrobial potential of disinfectants commonly used in dentistry to decontaminate heat-sensitive surgical guides. Ethylene oxide gas was used as the positive control; sterile water served as a negative control. Materials and Methods: Evaluation of CGs and LGs for bacterial contamination occurred soon after their arrival in the laboratory. Some guides went directly into tubes of trypticase soy broth solution, vortexed and equally divided into two tubes. One tube went into an 80°C bath for 19 minutes, while the other stayed at room temperature. After plating, half of the samples underwent anaerobic incubation. All incubation was for 48 hours at 37°C. Other guides underwent water rinsing or disinfection by various methods for 5 or 15 minutes or ethylene oxide gas sterilization prior to sampling. Results: Untreated CG specimens showed modest levels of bacterial contamination, with most colonies coming from liquid specimens not exposed to 80°C. LG specimens had more bacteria from both heat-treated and non-heat-treated aliquots. Chlorhexidine gluconate, diluted bleach, and water rinsing were not able to completely eliminate microorganisms on the specimens, but no viable microorganisms were present on specimens treated with gas sterilization or 70% ethanol for 15 minutes. Conclusion: CGs and LGs, on average, had different levels of bacterial contamination prior to disinfection. Water, chlorhexidine gluconate, and diluted bleach were not totally successful in decontaminating the surgical guides, but no growth was found after 15 minutes of immersion in 70% ethanol. Preferably, surgical guides should be submerged in 70% alcohol for a minimum of 15 minutes or undergo sterilization using ethylene oxide gas. Keywords: dental implants, disinfection, surgical guides