Chronic cough is a common symptom with significant morbidity. We report a case of a 51-year-old woman who presented with chronic cough. She recently had received a diagnosis of glaucoma and had started receiving therapy with topical latanoprost. The onset of cough coincided with the use of latanoprost. We performed a citric acid cough challenge while the patient was receiving latanoprost and repeated the challenge after therapy with the drug was stopped. The initial cough challenge revealed marked hypersensitivity of the cough reflex. After stopping therapy with latanoprost for 10 days, the cough sensitivity was reduced significantly. Within 3 days of recommencing therapy with latanoprost, the cough sensitivity increased to the initial value. This case illustrates that the topical application of latanoprost can markedly increase cough sensitivity, which is reversible on stopping administration of the drug. Moreover, the case reflects the clinical manifestation of the effect of topical latanoprost therapy on cough reflex, which, to our knowledge, has never been reported in the medical literature.