39 implant replacement arthroplasties were reviewed with a mean follow-up of 13 years. The study includes nine cases of partial replacement of the proximal pole of the scaphoid, 16 cases of total replacement of the scaphoid and 14 cases of replacement of the lunate. In 33 cases the conventional silicone elastomer (CSE) was used and in six the high performance elastomer (HP). Subjective, clinical and radiological evaluations gave different results. Respectively the results were excellent in 41, 23 and 5%, satisfactory in 41, 49 and 39% and poor in 18, 28 and 56% of the cases. Lytic lesions in carpal and/or pericarpal bones were present in all except two cases. Study of the X-rays chronologically revealed that they increased in number and size. Six cases had their implant removed. All had histologically proven silicone synovitis. A major secondary operation has been performed or is foreseen in all cases except one. We do not recommend implant replacement arthroplasty for the scaphoid or the lunate bone.