Repeated blood cultures were negative in a six-year-old boy with high septic temperature. Rheumatoid arthritis, typhoid and brucellosis were excluded. There was no evidence of leukaemia (bone-marrow tests). There was hepatomegaly with increased transaminase activity. Cortisone treatment was begun for suspected collagen disease. Several liver needle biopsies at first revelaed increasingly severe necrotising changes, predominantly in the centres of the acini. There were no parasites demonstrable histologically. The spleen was increased in the isotope scan but, covered by the liver, not definitely palpable. Diagnosis of mediterranean Kala-Azar disease was then suspected (the parents reporting a camping holiday in Yugoslavia) and finally proven serologically. The previously treatment-resistant disease improved dramatically after administration of trivalent antimony (Fuadin).