Genetic diversity measures support the conservation decisions aiming to maintain the genetic flexibility of animal populations and breeds. Many of these measures utilize neutral genetic markers and are based on classical concepts as coancestry and expected heterozygosity. As a component of genetic diversity, allelic richness is also important in conservation genetics. Its measurement requires that variations of sample size be taken into account using either the rarefaction and extrapolation techniques. Methods to estimate genetic diversity and allelic richness were compared in this study. DNA samples from 68 wild boars and 234 domestic pigs of the Duroc and Iberian breeds, including 63 animals of the Torbiscal and Guadyerbas Iberian lines, were genotyped for 18 microsatellites (one per autosome). As the results outline, the rank of these pig populations according to their contributions to the diversity will be different depending on the criteria utilized, because genetic diversity and private allelic richness do not exactly address the same type of diversity. Rarefaction and extrapolation-based techniques also produce partially discrepant results. The desirable integration of allelic richness into the diversity theory poses at the moment some unsolved difficulties.