To evaluate the utility of abdominal ultrasonography (AUS) to detect grossly evident masses in dogs with nontraumatic hemoabdomen. 94 client-owned dogs. Electronic medical records from 2014 to 2017 were searched to identify dogs with nontraumatic hemoabdomen that had an AUS performed by a radiologist and subsequently underwent gross evaluation by surgery or necropsy. Ultrasonography, surgery, and histology reports were reviewed, and descriptive statistics were performed. Sensitivity of ultrasonography to detect grossly identifiable masses was calculated. Differences were identified between AUS and surgical or necropsy findings for 51 of 94 (54%) dogs. Splenic masses were most commonly identified as the cause of hemoabdomen. Sensitivity of AUS was 87.4%, 37.3%, and 31.3% for masses in the spleen, liver, and mesentery, respectively. Five dogs had more lesions identified with AUS than were found on gross evaluation; 0 of 6 dogs with peritoneal diffuse nodular metastasis had lesions detected by AUS. In this sample of dogs, the utility of AUS to detect grossly identifiable lesions in dogs with nontraumatic hemoabdomen was limited, with the highest and lowest sensitivity found for splenic masses and diffuse nodular metastasis, respectively.