Termites (Isoptera) have a strong hierarchical structure due to their social organization. To interpret genetic differences within and among termite populations it is first necessary to create a quantitative scale to determine the meaning of “different.” To accomplish this, the entire hierarchy of genetic similarities in a Hawaiian population of Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) was defined by multilocus DNA fingerprinting using the oligonucleotide (GTG)₅ as a probe. The genetic background similarity in the population, based on the genetic similarity between unrelated termites, was 0.21 and falls in the range of other natural invertebrate and vertebrate populations. The mean genetic similarity of termites collected from the same collection site was 0.64 (range, 0.58–0.72). This equals an average relatedness of 0.54 within collection sites. The genetic similarity among the offspring of an artificially outbred laboratory colony lies in the same magnitude (0.65). However, genetic similarity within field colonies was significantly lower than the genetic similarity within laboratory colonies derived from pairs of siblings (mean 0.79). This indicates moderate inbreeding within most of the field colonies. This wide range of genetic similarities defines the basis for a detailed description of the population structure as well as the identification of individual colonies of C. formosanus.