Scientific illustration is a fundamental tool to convey scientific information. It is used in anatomical atlases and reference books, even when high-resolution photos could be used instead. Over the centuries, the study and representation of humans and animals improved in the anatomic field. This progress provided us with a broad set of reference images and the knowledge of how to communicate it to the readers. Modern illustration tools allow us to create pictures to illustrate concepts or results that otherwise would be very hard to explain, even using high-resolution photos. Our work presents the first of all Portuguese atlas of the laboratory mouse, moreover, in a different way from conventional. It begins from the outside to the inside, from bristles until inside the bones, presenting illustrations and histological images for each structure. Texts explain how the mouse organism works and its most common pathologies for each system. All the information is organized in an easy and mostly visual way to read that can reinforce the importance of the laboratory mouse. The number of subjects used on the production of the atlas was limited to the smallest amount necessary to do histological preparations and dissections, compromised with the 3 R's principles. For the illustrations, all the material was photographed and then stored, to be later used for consultation in the illustration process.