The patient is an 81 year-old male evaluated by ophthalmology for cataract surgery. The patient's eyes were dilated with one drop each of the anticholinergic agent tropicamide (Mydriacyl 0.5% ®), and the sympathomimetic agent, phenylephrine hydrochloride 2.5%. The combination solution, fluorescein sodium 0.25%/benoxinate hydrochloride 0.4% (FluorBenox ®), was also instilled in both eyes prior to tanometry. After several hours, the patient developed ocular redness and swelling, lasting one week in duration. On examination 3+ conjunctival injection, 2+ chemosis, and corneal immune infiltrates were seen. A similar reaction occurred one year prior, after dilation with phenylephrine hydrochloride. Patch tests were performed with the above ophthalmic solutions and a standard panel (T.R.U.E. Test ®) and were read at 48 and 96 hours. Strong positive reactions were documented for the phenylephrine hydrochloride 2.5% ophthalmic solution and four non- contributory compounds at 96 hours. The preservative in the phenylephrine solution, benzalkonium chloride 0.01%, was also an ingredient in the tropicamide solution, and thus was not the cause of the reaction. Allergic contact reactions to phenylephrine hydrochloride have rarely been reported in the literature despite its wide use. This patient's history, clinical findings and positive patch test results suggest a delayed type cell-mediated hypersensitivity reaction to phenylephrine. Ophthalmologists and allergists need to be aware that such hypersensitivity exists and should patch test patients who present with a similar history.