From November 1990 to June 1991, 33 cases of acute melioidosis were diagnosed in tropical Northern Territory, Australia during an exceptionally wet monsoon. Eighteen (55%) were alcoholic, 16 (48%) diabetic and only 4 (12%, all survivors) had no risk factors. Twenty-seven (82%) were considered recent infection, with an incubation period of 3-21 days (mean 14) documented in eight cases with presumed cutaneous inoculation. Fourteen patients presented with pneumonia (4 septicemic) and of 11 others with septicemia 4 had genitourinary foci. Three of 4 with splenic abscesses required splenectomy. Three had only skin/soft tissue infection. One patient with brainstem encephalitis needed prolonged ventilation. Overall mortality was 36% (12 cases, including three relapses), despite therapy with ceftazidime and intensive care facilities. Pseudomonas pseudomallei is the commonest diagnosed cause of fatal bacteremic pneumonia at Royal Darwin Hospital and emphasis is placed on early appropriate antibiotic therapy and compliance with maintenance therapy for at least three months.