A case of invasive multiple paranasal sinus aspergillosis with bony involvement is reported. A young immunocompetent lady presented with bilateral nasal obstruction due to polyps. Radiologically and histopathologically a fungal cause was kept a possibility, and the diagnosis of Aspegillus fumigatus was established by demonstration of acute angle branching septate hyphae on direct wet mount and repeated isolation in culture. Patient responded favourably to surgical excision of polyps and oral itraconazole post operatively.