Leptospirosis is a systemic infection usually producing fever with hepatorenal involvement, meningoencephalitis, and hemorrhage. In this article, we present three children between 10 and 13 years of age with leptospirosis. The purpose of this paper is to emphasize that leptospirosis is a problem in our country with farmers/cattle and that leptospirosis should be considered in certain ill children. The main symptoms were headache, fever, fatigue, abdominal pain and unconsciousness. Two patients had hepatic and renal involvement. The other had hepatic, pulmonary and probably pericardial. involvement. In all children spirochetes were demonstrated in blood and urine smears by dark-field microscopy and they were also isolated from urine and blood cultures by using Flecher medium. All patients were treated with penicillin; however, one subsequently required additional antibiotics due to Klebsiella pneumoniae septicemia. While one patient was discharged in a good health, the others were taken to their home by parents without completing treatment. In conclusion, we would like to emphasize that leptospirosis is still a public health problem in our region (Eastern Turkey) in where the majority of population are farmers and raise domestic animals such as cattle in rural areas. Additionally, leptospirosis should be considered in children admitted with headache, unconsciousness, fever and abdominal pain. (C) 2003 Tohoku University Medical Press.