[en] Since rubidium-81 has a half-life of 4.6 hours, osmium-191 of 16 days, and mercury-195m of 41.6 hours, the general utilization of daughters of these radionuclides is limited by the half-lives of the parents. There is the problem for centers to buy rubidium-81 every day. For osmium-191, it should be possible to purchase or manufacture a new generator every week or two. The 41.6-hour half-life of mercury 195-m is favorable so that generator can be transported and used for 3 to 4 days. Recent investigations concerning the advantages and disadvantages of use of these very short-lived radionuclides in nuclear medicine are discussed with respect to dosimetry, utility of the radionuclide generators, and dose-sparing. Studies employing these radionuclides in evaluation of respiratory cardiovascular and central nervous system diseases are critically evaluated