Various studies have revealed a positive effect of heterozygosity on developmental stability in animals of diverse taxa. In homeothermic vertebrates, however, no clear picture has so far emerged in this context. Here, we test the influence of heterozygosity on the developmental stability of adult-sized skulls of 63 Iberian hares (Lepus granatensis) from a Local population in Portugal. 44 allozyme and blood protein Loci were screened by horizontal starch gel electrophoresis, agarose electrophoresis, and isoelectric focusing. This yielded eleven polymorphic Loci, that were used to calculate individual heterozygosity. Levels of fluctuating asymmetry (FA) of three morphological character systems (15 epigenetic dental characters, ten non-metric skull traits, six metric skull variables) were determined and used as indicators of the levels of developmental homeostasis of single hares. Overall individual heterozygosity did not correlate with respective FA Levels in any of the three morphological character systems. However, a trend towards a negative relationship between metric FA and heterozygosity suggested that there might be a slight positive influence of heterozygosity on developmental stability of the morphometric system, but it could be masked by various seasonal exogenic factors.