Introduction: Anisocoria may develop due to physiological, pharmacological or neurological pathology. Neurological reasons which lead to pathological anisocoria are cases regarding sympathetic or parasympathetic innervation. In this article, we aimed to present a case of pharmacological anisocoria which is developed as a result of inhaler therapy containing ipratropium. Cases: Case 1; a 95 years old female patient. She was admitted to the hospital with dyspnea and general condition disorder. The patient was treated with bronchodilator containing ipratropium bromide, and on the sixth day of hospitalization, the left eye was mydriatic and there was no light reflex. There were direct and indirect light reflexes in the right eye, and the pupil diameter was normal. Case 2; a 68 years old male patient. He applied to the emergency department with confusion and general condition disorder. The patient was transferred to our intensive care unit with the diagnosis of upper gastrointestinal system bleeding. On the 11th day of his hospitalization, the patient was started on an inhaler containing ipratropium bromide, and 3 days later anisocoria was detected. His right eye was mydriatic. There was no light reflex. Cranial imaging was normal in both patients. The treatments of the patients whose history was uncharacteristic and no cause was found to explain anisocoria were compared. It was determined that nebulizer treatment containing ipratropium was applied to both patients. In the test with 1% pilocarpine solution for the differential diagnosis of pharmacological mydriasis, minimal pupil constriction was observed in the affected eye for both patients. After discontinuation of inhaler therapy; after 4 days in case 1 and after 3 days in case 2, the pupils were isochoric and light reflexes were normal. Discussion: In the differential diagnosis of anisocoria developing during intensive care follow-up, iatrogenic pharmacological side effects originating from the inhaler should be kept in mind as well as intracranial pathologies. The easy-to-perform pilocarpine test can prevent advanced diagnostic procedures and increased costs. [ABSTRACT FROM AUTHOR]