Abstract： To report a case of 16-month-old boy with anhidrotic ectodermal dysplasia with immunodeficiency who experienced disseminated herpes simplex infection. From 2 months of age, the patient experienced multiple pyrexial episodes of undetermined origin, which responded well to anti-inflammatory agents after undressed. Abnormal sweat with dry skin was noted; therefore, the skin biopsy of right axilla was performed at 7 months of age, and suggested a diagnosis of anhidrotic ectodermal dysplasia. Since 6 months of age, he developed recurrent upper respiratory infections and 2 episodes of pneumonia. Twenty days before, several glossal erosions occurred in the patient, supervened by painful and erosive eruptions and numerous blisters around the mouth and both hands with hyperpyrexia. Four days before, the patient was transferred to the department owing to skin lesion exacerbation. Cutaneous examination showed multiple crested or ulcerated plaques distributed eriorificially (mouth and nasal cavity) on the face. Several irregular, demarcated ulcers were scattered on the buttocks, scrotum and lower limbs, surrounded by grouped and umbilicated vesicles arising on erythema. Both hands were swelling, crusting and painful. Dentition was abnormal, and the patient had only 2 upper conical incisors. Routine investigation revealed that white cell count and C-reactive protein extremely elevated. Immunologic profile showed an abnormal distribution of lymphocyte subsets with decreased CD3+ T cells, CD8+ T cells and NK cells. Serum IgM level was slightly low. IgM antibodies to herpes simplex virus type 1 (HSV-1) were detected by serological testing. Based on the above-mentioned features, a diagnosis of anhidrotic ectodermal dysplasia with immunodeficiency and disseminated herpes simplex infection was confirmed. The patient was resolved favourahly after intravenous ganciclovir and antibiotics for 3 weeks without relapse of skin lesions.