Using stannous chloride, optimum conditions for $^{99m}Tc$ labelling of some scanning agents such as phytic acid (P A), dimercaptosuccinic acid (DMSA), and calcium diethylenetriaminepentaacetate (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 nearly constant $(500sim600{mu}g)$ regardless the variation of the molar ratios. It suggests that the given experimental conditions require about $500{mu}g$ 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 data showed characteristic patterns with each compound indicating that they are all suitable for the relevant scanning applications.