ABSTRACT Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare and potentially fatal adverse drug reaction associated with skin rash, fever, eosinophilia, and multiple organ injury. A number of pharmacological agents are known to cause DRESS syndrome such as allopurinol, anticonvulsants, vancomycin, trimethoprime-sulfamethoxazole, and pyrimethamine-sulfadiazine. Here, we describe two patients who developed DRESS syndrome during ocular treatment. The first case was being treated for late postoperative endophthalmitis with topical antibiotics, intravenous cephalothin, meropenem, and intravitreal injection of vancomycin and ceftazidime before symptoms developed. We were unable to identify the causal drug owing to the large number of medications concurrently administered. The second case presented with DRESS syndrome symptoms during ocular toxoplasmosis treatment. In this case, a clearer association with pyrimethamine-sulfadiazine was observed. As a result of the regular prescription of pharmacological agents associated with DRESS syndrome, ophthalmologists should be aware of the potentially serious complications of DRESS syndrome.