Purpose: The objective of this controlled exploratory cross-sectional study was to investigate and compare the presence of gene expression of bone resorption/remodelling in peri-implant crevicular fluid samples from healthy subjects and subjects showing obvious clinical and radiographic signs of peri-implantitis. Materials and methods: Peri-implant crevicular fluid (PICF) was sampled from seven healthy subjects and seven subjects with obvious clinical signs of peri-implantitis using paper points. The samples were analysed by quantitative polymerase chain reaction (qPCR). Biomarkers associated with bone degradation/remodelling, such as tartrate-resistant acid phosphatase (TRAP), dickkopf-related protein- 1 (DKK-1), osteoprotegerin (OPG), cathepsin K (CatK) and osteocalcin (OC), were of particular interest in the study. Results: The measured levels of genetic markers were similar for the subjects in the healthy and the peri-implantitis group. Only one subject out of seven with strong and clear clinical signs of periimplantitis exhibited a panel of genetic markers for ongoing bone degradation. This subject was also diagnosed with rheumatoid arthritis. Conclusion: The present data showed that patients with obvious clinical signs of peri-implantitis and a history of bone loss can exhibit similar gene expressions of bone loss/remodelling as clinically healthy implant patients. Absence of bone resorption markers demonstrated that it was not possible to establish ongoing bone degradation in six of seven subjects in the peri-implantitis group. The results suggest that bone resorption was not in progress at the time of PICF sampling, or that cells expressing such markers were not present in significant numbers at the site of PICF sampling. Schlagwörter: bone resorption, diagnosis, peri-implantitis, qPCR