: The authors report a case of adult orbital xanthogranuloma with associated adult-onset asthma in a 44-year-old man. Adult orbital xanthogranuloma was diagnosed on the basis of the clinical findings of bilateral, indurated, yellow eyelid lesions in a patient presenting with adult-onset asthma. Incisional biopsy of the eyelid lesions demonstrated a diffuse histiocytic infiltrate of the orbit and Touton giant cells without evidence of necrobiosis. Systemic evaluation failed to show evidence of bone lesions or paraproteinemia. When patients present with atypical indurated yellow eyelid lesions, a biopsy should be considered. If Touton giant cells are present, a systemic evaluation should be undertaken to rule out both Erdheim-Chester disease and necrobiotic xanthogranuloma. If no systemic findings are present, other than the possibility of adult-onset asthma, the rare entity of adult orbital xanthogranuloma should be considered.