Tricalcium phosphate (TCP) ceramic is known as bioresorbable bone substitute in orthopaedic field. Porous body of TCP has also high potential for application of drug delivery system in bony defect. Porous alpha-TCP can be easily fabricated through heat treatment of beta-TCP by conventional process, since alpha-TCP is thermodynamically stable phase at higher temperature than 1100degreesC. The problem is, however, that solubility of alpha-TCP is much higher than that of beta-TCP. Therefore dissolution of the porous alpha-TCP is liable to progress before bone defect is completely repaired. In the present study, we attempted to reduce dissolution rate of the porous alpha-TCP by coating with organic polymers. We fabricated porous alpha-TCP body with continuous pores of 10-50 gm in diameter through conventional heat treatment. The obtained porous body was coated with organic polymers including hydroxypropylcellulose (HPC) and sericin, a kind of silk protein. The porous body after the coating showed almost similar morphology to that before coating. Chemical durability was then examined in some buffered solutions with pH 4, 6 and 7.25. Dissolution of the specimens was estimated by measurement of Ca2+ ion in the buffer solutions after soaking. The results on dissolution of alpha-TCP in buffer solutions indicates that alpha-TCP coated with sericin shows the highest chemical durability. Compressive strength increased after coating with HPC. Thus prepared porous alpha-TCP is expected to be useful as a novel bone-substitute by incorporating with drugs or osteoinductive factors.