Purpose: To report a case of pansinusitis after swimming in a common pool. Case report: Acute sinusitis is ranked the fifth-most common indication for antibiotic prescriptions. Although sinusitis is often diagnosed clinically, cases that are resistant to conventional antibiotic therapy or recurrent cases may require diagnostic imaging in order to confirm the diagnosis. The complications of sinusitis, though rare, may lead to serious consequences if not diagnosed and treated early. We report a 33-year old man with pansinusitis presenting with a sudden onset of peripheral gaze diplopia associated with progressive frontal headache. His symptom resolved completely after he was given intravenous antibiotics and a nasal decongestant.