AbstractData has been presented on the loss of alleles from populations of small fixed size. Emphasis has been placed on the effect which the allele frequency distribution and the interlocus distribution of heterozygosity will have on the pattern of allelic loss. Rare alleles are rapidly lost during the initial sampling period, and continue to be lost for several generations following the establishment of small population size. The nonequilibrium nature of the process of loss of genetic variability is stressed. The rapid loss of rare alleles and the preservation of intermediate and high frequency alleles will result in (1) heterozygosity declining much more slowly than allele number, and (2) the establishment of genetically similar populations when sampled from the same base population.