The grey nurse shark (Carcharius taurus) is listed as threatened throughout much of its global distribution, and as critically endangered in eastern Australia. Captive breeding programs have thus far been largely unsuccessful and little is known of its mating system in this context. Here we carry out a paternity analysis to determine if the mating system in captivity is characterised by multiple mating, and whether poor offspring survival is associated with a particular male. Tissue samples from grey nurse sharks were collected from three potential sires, the two dams and nine pups housed at Manly SEA LIFE Sanctuary in eastern Australia. Each individual was genotyped at seven microsatellite markers and three cases of multiple paternity were inferred. No paternal link to stillborn (5), or scoliotic (2) pups was indicated. For the first time, we show the natural wild phenomenon of multiple paternity occurring in a captive environment.