Purpose: We evaluated a rapid preparation procedures for the labeling and quality control of 99mTc-ECD, MAG3, and MIBI using microwave heating and Sep-Pak cartridges. Materials and Methods: 99mTc labeling of ECD, MAG3, and MIBI kit preparation was performed according to the package inserts with microwave heating modification. Heating time was 10-15 sec, and heating was performed with 3 mm plastic bottle with screw cap to prevent radiation contamination. Labeling efficiency was obtained with C18 or Alumina N Sep-Pak cartridges. Results: The radiochemical purity of 93∼96% for 99mTc-ECD and 95∼99% for 99mTc-MIBI was obtained using Alumina N Sep-Pak cartridge. The optimum irradiation time of microwave method for 3 ml 99mTc-labeled radiopharmaceutical solution was 10 sec for 99mTc-ECD and 99mTc-MIBI, and 15 sec for 99mTc-MAG3. The results of quality control data with Sep-Pak cartridges were well correlated with TLC method. The total preparation time of these radiopharmcaeuticals was 5∼6 min including quality control procedure. Conclusion: This study demonstrates that radiopharmaceuticals preparation by microwave heating and quality control by Sep-Pak cartridges can be efficiently utilized as an alternative to the recommended method by manufacturer's manual. (Korean J Nucl Med 1999;33:430-8)