Objective · To investigate expressions of interleukin (IL) -1β, IL-6 and tumor necrosis factor-α (TNF-α) in sulcular fluid of peri-implantitis. Methods · Twenty-four patients with implant restoration were selected, including 12 patients in the peri-implantitis group and 12 patients in the peri-implant health group. Twelve healthy persons with healthy gingival tissues were taken as the control group. The levels of IL-1β, IL-6 and TNF-α in gingival crevicular fluid were detected by enzyme-linked immunosorbent assay. The correlations between the expressions of these cytokines and the amount of gingival crevicular fluid or the probing depth were analyzed. Results · The levels of IL-1β, IL-6 and TNF-α in the peri-implantitis group were significantly higher than those in the control group (all P<0.05). The expression levels of IL-1β and IL-6 in the peri-implantitis group were significantly higher than those in the peri-implant health group (both P<0.05). The level of TNF-α in the peri-implantitis group was positively correlated with the probing depth (r=0.600, P=0.039). Conclusion · The levels of IL-1β, IL-6 and TNF-α in gingival crevicular fluid are highly expressed in patients with peri-implantitis. The expression of TNF-α is positively correlated with the probing depth.