In a summarized report the development and testing of the ROTOP-MYOSPECT kit is described. After the argument on the necessity to involve a99mTc-complex for the assessment of a myocardial perfusion situation the chemical problems are discussed. The reduction of pertechnetate generator eluate takes place during reconstitution of the kit by the ligand DMPE *2 HCl in aqueous/alcoholic solution at pH 2 and 125 °C. A cationic Tc-compound has been developed providing well-assessable images of myocardium using the SPECT technique and can be applied for a number of diagnostic problems. In comparison to Tl-SPECT images and the non-invasive coronary angiography a high sensitivity is attained. As an example for application the case control before and after bypass operation is discussed and the fitness of the radiopharmaceutical is proved.