BACKGROUND To elucidate retrospectively the risk factors for bronchopleural fistulae after lung cancer surgery. METHODS The subjects were 1,177 patients with lung cancer who underwent surgery between 1983 and 1997. Twenty-two clinical factors were examined by logistic analysis. RESULTS Bronchopleural fistulae were observed in 35 patients (32 males, 3 females) with a mean age of 64 years. Eighteen (51%) of 35 patients died of BPF-related complications. The significant risk factors obtained by univariate analysis were male gender, heavy smoking, current smoking, low level of %FVC, metastases to lymph nodes, squamous cell carcinoma, increased WBC, decreased albumin, advanced postsurgical stage, sleeve lobectomy, and resection of the right lower lobe or middle and lower lobe. The significant risk factors noted by multivariate analysis were heavy smoking (30 or more pack/years), current rather than past smoking, metastases to lymph nodes, decreased albumin (3.5 mg/dl or less), and resection of the right lower lobe or middle and lower lobe. CONCLUSIONS The above risk factors must be taken into account before surgical techniques followed by adequate perioperative management are selected.