An 8-month-old neutered female domestic mixed breed cat was presented to Dr. L. Kriaučeliūnas Small Animal Clinic due to coughing that persisted for 2 weeks. Lateral and dorsoventral chest radiographs revealed an unusual dome-shaped soft tissue opacity mass that had contact with the cranial part of the diaphragm. Together with heart and abdominal ultrasound findings, we decided that one of the differential diagnoses was a diaphragmatic hernia. During the diagnostic celiotomy, a vertical 4 cm in length diaphragmatic deficit was visualized. Left medial and lateral liver lobes were herniated, yet healthylooking. Adhesions between the liver lobes and the pericardium sac were visualized and dissected. The pericardium was sutured with simple interrupted suture pattern. A herniorrhaphy was performed suturing the diaphragm with the continuous suture pattern. Successful surgical treatment resulted in fully resolved clinical symptoms.