Genetic mating systems described for squamate reptiles range from primarily monogamous to completely polygynandrous. The presence of female multiple mating is almost ubiquitous among squamates and even occurs, albeit at a low rate, in socially monogamous species. Here we examine the genetic mating system of the territorial tawny dragon lizard (Ctenophorus decresii). Paternity was assigned to captive-born hatchlings using eight microsatellite loci, revealing a 4% rate of multiple paternity. One-quarter of males sired more than one clutch, although multiple mating by males is likely underestimated. The rate of multiple paternity in C. decresii represents one of the lowest among squamates and may be a result of successful male territoriality. However, the observed low rate of multiple paternity does not eliminate the possibility of widespread female multiple mating due to the potential for sperm storage and sperm competition. We conclude that the tawny dragon lizard employs a predominantly polygynous genetic mating system.