A 72-year-old man with a history of metastatic melanoma presented with a two-day history of erythematous and edematous plaques, with scattered bullae on the neck, chest, axillae, and inguinal and gluteal folds, which began five days after infusion of an experimental drug. The clinical and histopathologic findings were consistent with systemic drug-related intertriginous and flexural exanthema (SDRIFE), which is an uncommon drug reaction that results in symmetric erythema that affects the buttocks, groin, and/or thighs as well other flexural folds. The clinical manifestations of SDRIFE are highly characteristic and include distinctive primary cutaneous lesions with a specific distribution and course; however, heterogeneity exists with respect to histopathologic features, skin test results, and in vitro investigations. The exact mechanism of SDRIFE remains unknown but is thought to result from a type IV delayed hypersensitivity immune response. Treatment is symptomatic and includes topical or oral glucocorticoids.