The aim of this study was to determine interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) levels and neutrophil elastase (NE) activity in peri-implant crevicular fluid (PICF) of smoker and nonsmoker patients, and to investigate their relationships with clinical parameters. A total of 42 endosseous root-form dental implants of 14 patients were clinically examined by modified Plaque index (PI), modified Gingival index (GI) and probing depth (PD). Smoking habits of the patients were recorded. PICF of implants were collected by Periopaper strips and IL-1β, TNF-α levels were determined by enzyme-linked immunosorbent assay (ELISA). NE was analyzed with a neutrophil specific chromogenic substrate, N-methoxysuccinyl-Ala-Ala-Pro-Val-p- nitroanilide. The cytokine and enzyme levels in PICF were expressed as total amount/activity and as concentrations. NE activity in PICF significantly correlated with GI and PD, and IL-1β levels with GI and PICF volume (P < 0.05). The correlations were stronger when the PICF levels were expressed as total IL-1β amount and as total NE activity. The implants with inflamed gingiva (GI > 1) had higher levels of IL-1β and NE activity than implants with noninflamed or slightly inflamed gingiva (GI ≤ 1) (P < 0.05). Total NE activity in implants with deep pockets (PD > 3 mm) was greater than the implants with shallow pockets (PD ≤ 3 mm) (P < 0.05). The implants of smoker patients had significantly lower PICF NE activity and IL-1β levels, and significantly higher TNF-α levels than the implants of nonsmokers (P < 0.05). The findings of the present study indicate that NE activity and IL-1β levels in PICF may be used to measure implant health status of patients who do not smoke. Copyright © Blackwell Munksgaard 2002.