Using stannous chloride, optimum conditions for Tc-99m labelling of some scanning agents such as phytic acid(PA), dimercaptosuccinic acid(DMSA), and calcium diethylenetriaminep- entaacetate(Ca-DPTA) were established. Methods of separation and identification of the labelled compounds were practiced by a paper- or thin layer- chromatography. Biodynamic studies of the compounds were also carried out. The results indicate that the molar ratios of the chelating agent and stannous chloride varies only with the concentrations of the chelating agents, and thus the amounts of the stannous chloride per labelling tube were neatly constant(500∼600 μg) regardless the variation of the molar ratios. It suggests that the given experimental conditions require about 500 μg of stannous chloride regardless of the chelating agents. Under alkaline pH, the labelling yields were drastically decreased due to the probable formation of colloidal tin compounds. Biodynamic clara showed characteristic patterns with each compound indicating that they are all suitable far the relevant scanning applications.