A 28-year-old man who had suffered from erythropoietic protoporphyria since infancy was referred because of worsening photosensitivity. Conventional therapy with beta-carotene, terfenadine and topical sunscreens was ineffective or not tolerated, and he was treated with transfusions of washed packed cells. Unexpectedly, his photosensitivity deteriorated further, his whole blood protoporphyrin levels doubled and he developed abnormal liver function tests. This is the first report of such an adverse response to blood transfusion therapy for erythropoietic protoporphyria and may have been related to subclinical hepatitis or the increased iron load associated with blood transfusion.