To determine the incidence of fever and bacteremia following flexible bronchoscopy, we analyzed the medical records of 111 patients who had undergone flexible bronchoscopy from 1988 to 1990. Seventy-seven of these patients underwent other procedures besides biopsy at the time of flexible bronchoscopy: washing cytology in 29, brushing cytology in 23, washing and brushing cytology in 23, and bronchoalveolar lavage in 2. Twenty patients (18%) developed a fever (>37.5°C), which subsided within 24 h. No patient developed pneumonia. There was no correlation between the incidence of fever and the number of biopsies. We then prospectively studied 44 patients who underwent flexible bronchoscopy from March 1991 to October 1991. Immediately after bronchoscopic examination, venous blood was obtained for blood culture. There was only one positive culture with gram-positive rods, but the patient had neither fever nor pneumonia. Five patients had a fever >38.0°C, but it subsided within 24 h, and no patient developed infectious diseases. We conclude that the incidence of fever and bacteremia following flexible bronchoscopy is low, and there would be no benefit from the prophylactic use of antibiotics in these patients.