Background: Primary sarcoma of the lung is a very rare malignant tumor accounting for less than 0.5% of all lung tumors and presenting diagnostic and treatment challenge. We describe a case of a patient diagnosed with primary lung undifferentiated pleomorphic sarcoma developing subsequent peritoneal and small bowel metastases, which stand for highly unusual disease presentation. Case presentation: A 57-year-old male presented with extensive partially necrotic tumor in the left upper lobe (LUL) of the lung that involved LUL bronchus and extended to the visceral pleura. There was no evidence of nodal or visceral dissemination. After initial presentation, the patient was admitted to the hospital’s pulmonology department for further workup. The most likely diagnosis based on biopsy specimen was poorly differentiated sarcoma. Left pneumonectomy with mediastinal lymph node dissection was performed. The final pathohistological diagnosis (PHD) was undifferentiated pleomorphic sarcoma (UPS). Three months after lung surgery, a follow-up CT scan was done which showed a 60-mm obstructive metastatic intraabdominal lesion with small bowel infiltration and further separate peritoneal deposits. Unfortunately, an urgent surgery had to be performed as the patient developed signs of acute abdomen due to bowel perforation. Only 2 months later, the patient passed away at home. Conclusions: Treatment options of UPS are based on algorithms used in treatment of extremity lesions with wellestablished role of surgery. However, the role of perioperative chemotherapy remains equivocal with no strong evidence-based data due to the rarity of the disease. Small bowel is an unexpected metastatic site, but of significant clinical relevance