We report a family with autosomal dominant inherited neutropenia, characterized by maturation arrest of neutrophil precursors and hypergammaglobulinaemia. A mother, two children by her first marriage and two by her second were affected. They suffered recurrent lung, skin, ear and periodontal infections. Four have had appendicitis, and three mastoiditis. One died at 7 years from neutropenic enterocolitis, and a second at 10 years from small bowel infarction. Four who were treated with rhG-CSF responded to 5-14 micrograms/kg/day with normal neutrophil counts. Daily therapy has maintained neutrophil counts above 1000 x 10(9) per litre. Elective appendicectomy and long term G-CSF therapy are indicated.