SummaryWe describe a 44 years old patient who developed severe non-oliguric acute renal failure associated with pneumopathy, respiratory distress and severe cerebral disturbance.Transient leucocytosis, thrombocytopenia, hyponatremia and abnormal liver function tests were the chief biological findings.The diagnosis of Legionnaires’Disease was based on a rising titer of antibodies againstL. pneumophilaas. determined by indirect immunofluorescence employing several serogroups. Renal biopsy revealed actue tubulointerstitial nephritis.He was treated with dialysis, mechanical ventilation, prednisone and erythromycin.