Monogamy and inbreeding are often thought to characterize the breeding system of termite societies. However, few studies have employed genetic markers to ascertain either the genetic structure of single colonies or the extent of local inbreeding. This study employs allozyme analysis to investigate the breeding system of Nasutitermes nigriceps with respect to the number of reproductives contributing to single colonies, and the level of inbreeding within and among local colonies. The majority of the 136 nests examined from three study sites showed patterns of protein polymorphism consistent with their origin from a single mated pair, establishing that monogamy is indeed the predominant mode of reproduction. A small proportion of colonies (N=7) had genotypic frequencies suggesting that offspring were not all full-siblings. The genetic composition of all colonies appeared stable through a one-year interval, suggesting that the observed genetic attributes represent relatively persistent reproductive associations. Wright's (1978) F-statistics showed moderate differentiation among study sites, indicative of restricted gene flow and the occurrence of inbreeding at a regional scale. However, mating appeared to be random at single sites as the inferred genotypic frequencies of colony progenitors did not deviate from Hardy–Weinberg expectations, indicating little inbreeding in the study populations.