Determination of glycosaminoglycans (GAGs) in peri-implant sulcus fluid (PISF) may monitor tissue changes around implants. This study investigated osseointegrated IMZ titanium implants at five stages from initial exposure to occlusal loading from prostheses. Two peri-implant sulcus fluid glycosaminoglycans (PISF GAGs), hyaluronic acid (HA) and chondroitin-4 sulfate (CS), were determined by cellulose acetate electrophoresis and densitometric scanning. Compared to longer-serving implants, CS contents at early stages was higher and with full occlusal loading was three times greater, without significant changes in HA contents. These observations appeared to reflect predominantly responses in the supporting bone, particularly when compared to our previous studies on ceramic implants and teeth affected by periodontal disease. This study supports the potential of PISF GAG analysis to detect adverse tissue responses, notably bone resorption. Schlagwörter: dental implants, glycosaminoglycans, implant monitoring, peri-implant sulcus fluid