Pneumosinus dilatans is a rare disease characterized by air-filled expansion of a paranasal sinus. Approximately 134 cases are reported in the literature, but not only one associated with infantile cerebral palsy (ICP) and nasal polyposis. We herein present this case report aimed to further characterize this uncommon condition: a 28-year-old female diagnosed with infantile cerebral palsy and nasal pol-yposis, in whom the cranio-facial CT scan revealed the association of a pneumosinus dilatans involving the frontal sinus. The patient is currently undergoing a protocol for endoscopic surgery of the nose and paranasal sinuses.KEYWORDS: pneumosinus dilatans, polyposis, infantile cerebral palsy