Melioidosis, which is infection with the gram-negative bacterium Burkholderia pseudomallei, is an important cause of sepsis in east Asia and northern Australia. In northeastern Thailand, melioidosis accounts for 20% of all community-acquired septicaemias, and causes death in 40% of treated patients. B pseudomallei is an environmental saprophyte found in wet soils. It mostly infects adults with an underlying predisposing condition, mainly diabetes mellitus. Melioidosis is characterised by formation of abscesses, especially in the lungs, liver, spleen, skeletal muscle, and prostate. In a third of paediatric cases in southeast Asia, the disease presents as parotid abscess. In northern Australia, 4% of patients present with brain stem encephalitis. Ceftazidime is the treatment of choice for severe melioidosis, but response to high dose parenteral treatment is slow (median time to abatement of fever 9 days). Maintenance antibiotic treatment is with a four-drug regimen of chloramphenicol, doxycycline, and trimethoprim-sulfamethoxazole, or with amoxicillin-clavulanate in children and pregnant women. However, even with 20 weeks' antibiotic treatment, 10% of patients relapse. With improvements in health care and diagnostic microbiology in endemic areas of Asia, and increased travel, melioidosis will probably be recognised increasingly during the next decade.