The synthesis of a rhenium-MDP labelled compound using carrier-free Re-188 from the W-188/Re-188 generator was investigated. Stannous chloride was used as the reducing agent for the reduction of rhenium. Dependence of the yield of Re-MDP upon the concentration of reducing agent, reaction time, antioxidant, pH, temperature, ionic strength and adding the carrier was examined. Under optimum conditions, the yields of Re-MDP were 85-89% using carrier-free Re-188 and 92-95% using carrier-added Re-188. Furthermore, the stability of Re-MDP at different pHs was studied.