Sinonasal tumors can invade into the critical structures of the anterior and central skull base. Although the determination of precise tumor histology is difficult with imaging, radiology is important in helping differentiate malignant from benign disease. Imaging helps to map the anatomical extent of intracranial and intraorbital tumor, which has important implications for staging, treatment and prognosis. Imaging also helps to facilitate and plan for craniofacial or endoscopic surgical approaches and radiation planning. This paper will review the locoregional invasion patterns for sinonasal tumors, with emphasis on their imaging features. The authors will discuss the implications for staging, resection potential, choice and details of radiotherapy with or without chemotherapy and prognosis. The imaging assessment of structures and compartments that are critical to the skull base team are highlighted: orbit, cavernous sinus, anterior cranial fossa dura/intracranial tumor, lateral frontal sinus, vascular tumor encasement, perineural tumor spread and tumor effect on the surrounding bony structures.