The bone response to a noncemented knee prosthesis was observed by quantified isotopic gammagraphy. One hundred six sequential scintimetric explorations were performed in 36 patients with total knee arthroplasty. Fifteen areas of interest were taken into consideration and their gammagraphic analyses were compared with radiologic findings during a postsurgery period of 24 months. Starting with a very high radionuclide uptake level obtained in the first postsurgery level, a gradual decrease was correlated with osteoblastic activity. In this first evaluation, the gammagraphic response around the implant is different in biologic prostheses than in cemented ones. These data may be useful for evaluating implants in orthopedic surgery.