In this study, the insulin adsorption ability by synthetic hydroxyapatite was investigated. Hydroxyapatite before thermal treatment and heated at 900°C and 1100°C were incubated in a solution containing 32 mg insulin/gHA. Adsorption and desorption experiments were carried out at 37°C under constant and slowly stirring. From FTIR results it was observed that insulin was tightly attached to HA surface after 96 hours adsorption experiment. Thermal pre-treatment on HA samples had no effect on insulin adsorption. However, protein desorption was more pronounced on samples not submitted to thermal treatment.