Radionuclide cardiac studies lend themselves exceptionally well to functional imaging. This is especially true for gated blood pool scan (GBP). Making functional images is also possible in radionuclide angiocardiography (RNAC). In this study we tried to validate the functional images obtained from RNAC by comparing it with GBP. Twenty three patients (16 patients with coranary artery diseases, 5 with hypertensive heart diseases, and 2 with nonspecific chest pains) underwent simultaneous RNAC and GBP at the sarne position (LAO 45). From both studies, global ejection fraction, regional ejection fraction, phase image, amplitude image, stroke image, paradox image, maximum ejection and maximum filling rates were obtained. Global ejection fraction are almost same in both studies. Regional ejection f#ractions of apex and inferior portion af left ventricle calculated frorn RNAC are well correlated with those of GBP. Phase and paradox image, maximum ejection and maximum filling rates were obtained. Global ejection iraction are almost same in both studies. Regional ejection fractions of apex and inferior portion of left ventricle calculated from RNAC are well correlated with those of GBP. Phase and paradox images of RNAC are very similar to those of GBP. However, amplitude and stroke images are different. Regional ejection fractions of the left ventricular base, rnaximum ejection and maximum filling rates obtained from RNAC are significantly different from those of GBP. In conclusion, albeit all of functiona! images of RNAC is not same as (BP, regionai wall motions and global left ventricular function are expected to be successfully analyzed by phase and paradox image and ejection fraction.