This investigation had 2 aims: 1) to determine the levels of acute‐phase proteins and immunoglobulin G (IgG) against Porphyromonas gingivalis in peri‐implant crevicular fluid (PICF) and their association with the clinical condition of the peri‐implant mucosa; and 2) to compare the inflammatory and immunological responses at implants and teeth as reflected by the gingival crevicular fluid (GCF) and PICF levels of acute‐phase proteins and immunoglobulins. Thirty‐one partially edentulous subjects were recruited for this study. PICF was sampled from 1 healthy and 1 inflamed site from each patient; GCF was sampled from an additional 21 healthy and 27 inflamed tooth sites of the same patients. GCF and PICF were collected with paper strips (for 30 s) and analysed using enzyme‐linked immunosorbent assays for α2‐macroglobulin, α1‐antitrypsin, transferrin, lactoferrin and IgG againstP. gingivalis. This investigation demonstrated that the absolute amounts of the acute‐phase proteins and IgG againstP. gingivalisare higher in GCF and PICF from inflamed than healthy sites. No significant differences were observed between PICF and GCF components at either healthy or inflamed sites, suggesting that inflammatory and immune events are similar in the peri‐implant mucosa and gingiva in humans and that PICF and GCF production is governed