Sinonasal inverted papilloma (IP) is a primary benign lesion with a tendency for local recurrence. Malignant transformation may develop in up to 15% of cases. Fascin (Fascin 1) is an actin cross-link binding protein required for the formation of actin-based cell-surface protrusions and cell motility. Fascin up-regulation in lung, gastric, breast and hepatobiliary carcinomas correlates with aggressiveness and decreased survival. Here we evaluate immunohistochemical expression of fascin in 47 sinonasal IPs from 34 patients. Fascin over-expression is significantly more common in sinonasal IP with high-grade dysplasia than in those with no dysplastic or low-grade dysplastic epithelium (P = 0.0001). No significant change in fascin expression is seen with recurrence. Over expression of fascin in high-grade dysplastic epithelium in IP may be associated with tumor progression and malignant transformation.