<p>Peritoneal surface malignancies are a heterogeneous group of neoplasms originating from the peritoneum or spreading to the peritoneum from a distant primary. Primary peritoneal neoplasms are a subgroup of rare lesions that develop from peritoneal cells in patients without underlying malignancy. More frequently, the peritoneal cavity is secondarily involved by a primary gastrointestinal or gynaecological malignancy, usually by transcoelomic spread. Due to their similar presenting symptoms and imaging appearances, it is challenging to distinguish primary peritoneal malignancies from peritoneal metastases. These neoplastic entities may also be mistaken for benign peritoneal diseases, which can delay diagnosis and consequently management. Innovative surgical procedures for aggressive disease control have increased the importance of accurate preoperative workup of peritoneal malignancies. Cross-sectional imaging aids in lesion characterization, local staging, choosing the optimal surgical approach, and prognostication. As part of the multidisciplinary team managing these entities, radiologists should be aware of these imaging appearances while avoiding potential mimics, and also serve as a guide to the surgeon for planning surgical resection.</p>