Aim of the work: the present work was designed to study the anatomical structure of the skull of three mammalian animals live in Egypt. These animals were Guinea Pig (Cavia porcellus), Hedgehog (Hemiechinus auritus) and Least Weasel (Mustela nivalis vulgaris). It is worth mentioning that these animals are having different diets since, Cavia porcellus is herbivorous, Hemiechinus auritus is insectivorousand Mustela nivalis vulgaris is carnivorous. Materials and methods: heads of the three animals (Cavia porcellus, Hemiechinus auritus and Mustela nivalis vulgaris) were used to study the anatomical structure of the skull and mandible in each animal. Results: after preparation of each skull of the animals under investigation, it was photographed and described according to the different views; dorsal, ventral, lateral and occipital in addition to the lower jaw. It is worth mentioned that these animals had different diets. So, some differences were observed in the facial and cranial regions of the skulls in the three animals. The parietals and frontals in the skull of Cavia porcellus were slightly convex and the skull had a broad zygomatic arch. The skull of Hemiechinus auritus had a long facial region and the tympanic bulla was not well developed. The skull of Mustela nivalis had short facial region and long cranial region which had an obvious prominent sagittal crest. The lower jaw had two mandibles which were connected firmly by bony mandibular symphysis. Also, heterodont teeth were arranged on the upper and lower jaws.