The case of a 28-year old woman with pruritic and erythematous eruptions on the knees and ankle about 10 days after being stung by sea urchin is reported. The spines of a sea urchin were ground, extracted and patch-tested, to which the patient showed a positive delayed skin reaction. Based on the clinical course and positive patch tests, it was concluded that the patient developed a delayed hypersensitivity reaction to the sea urchin's stinger.