Tularemia is a rarely reported disease that can cause water-borne epidemics in Turkey. Tularemia was suspected in five patients with the same complaints admitted to Gerede Governmental Hospital from the same village in the same week. Tularemia antibodies were negative in the early period, however, seroconversion was detected in four patients after four months. The village was visited to investigate the source and size of the outbreak in the week the patients were admitted as well as in the fourth month. As a result of investigation, 21 of 108 villagers, including the first five patients, were found as affected from the outbreak. Tularemia antibodies were detected in dilutions as > 1/80 in 17 patients and 1/40 in one patient while three persons were seronegative. In 17 symptomatic patients, cervical lymphadenopathy, fever, sore throat, conjunctivitis, skin eruption and cough were determined in 17, 14, 13, eight, four and one patient(s), respectively. Four patients had no symptoms. All patients profited from the aminoglycoside plus tetracycline therapy. Examination of the pipe- and three spring-waters revealed that all the water sources were contaminated bacteriologically, however, Francisella tularensis could not be isolated on glycose-cystine medium. In conclusion, the patients had been misdiagnosed at the beginning of the outbreak because tularemia had not been reported in Bolu Province until that date, but it should be considered in the differential diagnosis in the cases admitted with the above complaints.