Objective-To determine ultrasonographic features and reference values of the anatomy of the abdomen of common rats (Rattus norvegicus). Animals-20 adult male and 20 adult female rats. Procedures-A complete abdominal ultrasonographic examination was performed with the rats sedated. The cadavers of 4 rats were used for anatomic comparisons. Two cadavers were dissected and 2 cadavers were frozen and then cross-sectioned by use of an electric bandsaw. Slices were cleaned with water and photographed on each side. Correlations between variables were determined. Results-The ultrasonographic anatomy of the abdomen was determined, including measurements of the kidneys and adrenal glands and thickness of the walls of the stomach (saccus caecus, fundus, and pylorus), duodenum, and cecum. A significant positive correlation between kidney size and body weight was detected. The dorsoventral measurements of the left and right adrenal gland were significantly different, regardless of sex. Dorsoventral measurements of the right adrenal gland were significantly different between males and females. Conclusions and Clinical Relevance-The ultrasonographic images and data provided an atlas of the ultrasonographic anatomy of common rats that may be useful to veterinary radiologists, clinicians, and researchers.