The tammar wallaby has a polygynous mating system in which the dominant male usually controls initial access to oestrous females by mating first and then guarding the female from the advances of other subordinate males. In this study we used DNA fingerprinting with a human 3' hypervariable region (HVR) alpha globin probe to examine the paternity of pouch young progeny from 13 female tammars that were given continual access during the breeding season to a group of four sexually mature males. Constant individual-specific DNA profiles were observed for each animal. Paternity for 22 pouch young was successfully assigned using visual and computer-based analyses. However, no statistical difference was observed between the number of young sired by any of the four males (χ2 = 2, d.f. = 3, P > 0.1). Mate guarding by the dominant male in our captive breeding group was not, therefore, sufficient to prevent successful subsequent matings by subordinates nor to enhance the genetic contribution of this male to the next generation. In each analysis, visual and computer assignments of paternity coincided, and these concurred with the results of a relatedness test which found that a large number of DNA bands were shared by sires and their progeny. The results from this paternity study show that first mating and subsequent mate guarding by the dominant male tammar wallaby in our captive group do not significantly skew the outcome of paternity towards this male and away from other males that subsequently mate with each female.