Mesothelioma is the most common malignant primary tumor of the pleura and usually associated with inhalation of asbestos fibers. In contrast, peritoneal mesothelioma is a rare entity whose pathomechanism is not yet fully understood. The coexistence of pleural mesothelioma with secondary involvement of the abdominal cavity has not been addressed in the literature. In this case report, we describe secondary malignant mesothelioma of the greater omentum. A 69-year-old man with histologically proven pleural mesothelioma on the right side and no past medical history of asbestos exposure received palliative treatment consisting of a talc pleurodesis. After a 6-month interval of stable disease, a local progressive tumor of the right pleura was seen on a CT scan. Eleven months later, during follow-up, the patient presented at our emergency department with a sudden onset of diffuse abdominal pain. Abdominal ultrasound revealed a mass within the greater omentum and the coexistence of free fluid. Subsequent abdominal CT scans demonstrated tumor infiltration from the right pleura by a transdiaphragmatic route into the abdomen, where diffuse infiltration of the greater omentum was observed. Aspiration of the ascites and the biopsy of the greater omentum confirmed the diagnosis of secondary malignant mesothelioma of the peritoneum. In conclusion, we present the extremely rare diagnosis of secondary malignant mesothelioma of the abdomen, which arose as a result of local progression from the right pleura into the abdomen.