We reported a 47-year-old female with congestive heart failure (CHF) of unknown origin. In this case, it was suggested that 123I-BMIPP and 99mTc-tetrofosmin myocardial SPECT images were useful in the diagnosis of CHF of unknown origin. She had complained of easy fatigability and dyspnea on effort since Sep. 1995. She was admitted to our hospital because of worsening of symptoms in Dec. 1995. Slightly decreased uptake in anterior, lateral and apical walls was recognized in 99mTc-tetrofosmin SPECT images, meanwhile 123I-BMIPP SPECT images showed markedly reduced uptake in the same areas. This discordance in the distribution between 123I-BMIPP and 99mTc-tetrofosmin myocardial SPECT suggested that CHF was not due to dilated cardiomyopathy, but ischemic myocardial disease. Coronary angiography revealed 90% stenosis at the just proximal of left coronary artery. This case was diagnosed an isolated coronary ostial stenosis with CHF, because she was menstruated middle aged woman and did not have a history of aortitis syndrome, syphilis and coronary risk factor before.