Decay rate data of mixed fission products are presented from thermal neutron fission of 233U, 235U, and 239Pu and from fast fission of 238U and 232Th in the absence of neutron absorption by the fission products. The effect of neutron absorption by the fission products on decay rate is shown to be relatively small for conditions that exceed current light water reactor conditions. Decay heat data from fission products of 233U and 232Th in the absence of neutron absorption are provided which supplement similar data for 235U, 238U, and 239Pu given in the new American National Standards Institute/American Nuclear Society 5.1 Standard.