Genetic polymorphism was detected in the red deer (Cervus elaphus L.), plasma proteins, plasminogen (PLG) and vitamin D binding protein (GC) using antiserum to human proteins. The affinity of the antisera to deer plasma was less than 10% that of a human standard but they bound specifically to proteins of molecular weight expected for GC and PLG. Three codominant alleles of GC and five of PLG were observed. In a set 124 farmed deer calves and their parents, six calves had genotypes which were not consistent with the expectations of inheritance. Further inconsistencies were found when variation in isocitrate dehydrogenase (IDH) and transferrin (TRF) was examined. Using genetic models which included pedigree error parameters the data were shown to be consistent with genetic inheritance of all loci in a data set containing approximately 4.8% (SE 1.4%) parent-progeny pedigree mismatches. In samples from four deer populations representative of the red deer introduced to New Zealand the GC and PLG polymorphisms provided a probability of paternity exclusion (PE) of between 0.34 and 0.54 and when IDH and TRF were also included the PE was between 0.46 and 0.66. The four populations differed significantly in allele frequency, which supports historical evidence that they originate from separate introductions of small numbers of European red deer.