Leptospirosis is rarely reported in children. It is easily treated with antibiotics but can be fatal if treatment is delayed. A 12-year-old girl was diagnosed with Weil syndrome, a severe form of leptospirosis, 10 days after returning from Mainland China. She presented with fever, hypotension, jaundice, and acute renal failure. She had used well water for bathing and swum in freshwater.