DNA fingerprinting was used to study paternity and genetic variability within a captive flock of Whooping Cranes (Grus americana). Fingerprint patterns for 42 individuals were obtained by digesting genomic crane DNAs with HaeIII followed by electrophoresis, blotting, and hybridization to the M13 minisatellite probe. Despite finding reduced levels of genetic variation in the Whooping Crane due to a population "bottleneck," these polymorphisms were successfully used to determine paternity in six of seven cases of captive propagation where the maternal-offspring relationship was known, but where the sire was unknown. These determinations of paternity are required for effective genetic management of the crane flock. These results also revealed a number of heterozygous minisatellite loci that will be valuable in future assessments of genetic variability in this endangered species.