The objective of this study was to identify and compare the subgingival bacterial population around Brånemark implants and natural teeth using an enzymatic test (kit SK-013, Periocheck) to determine the trypsin-like activity of the subgingival bacterial population. Significant difference was seen between SK-013 activity and increased probing depth for both teeth and implants. The morphologic bacterial composition in subgingival plaque samples was examined by phase contrast microscopy. Spirochetes were conspicuously absent around implants in totally edentulous patients, but were present in those from partially edentulous patients. The present study indicates that the use of SK-013 to determine the trypsin-like enzymatic activity of dental plaque around implants is a simple and useful method and is similar to counting motile rods and spirochetes. Schlagwörter: Brånemark implants, enzymatic activity, peri-implant condition, subgingival microbial flora