The purpose of this study was to compare the accuracy and agreement of whole-body positron-emission tomography (PET) scan to bone scintigraphy for the detection of bony metastases in staging patients with newly diagnosed lung cancer. The tumor registry and nuclear medicine database at our institution were queried and identified all patients between July 1998 and August 2002 with a new diagnosis of lung cancer, a whole-body 2-deoxy-2-[18F]fluoro-D-glucose (FDG)-PET scan, and a bone scan prior to therapy. All of these patients' radiologic reports were then retrospectively reviewed, and confirmation of bone metastases was determined by consideration of all available clinical information. The sensitivity, specificity, and accuracy for each study were then calculated. Two hundred and fifty-seven patients fulfilled the entrance criteria. One hundred and four patients (40%) presented with stage IV disease, and bone metastases were confirmed in 57 (22%) patients. The accuracies of PET and bone scan were 94 and 85% (P < 0.05), sensitivity values were 91 and 75%, and specificity values were 96 and 95%, respectively. The weighted-kappa statistic suggested moderate agreement between the two modalities KW = 0.510, 95% CI, 0.402-0.618). The use of both whole-body PET and bone scintigraphy as initial staging studies in lung cancer patients provides redundant information about the presence of bony metastases. The improvement in accuracy and sensitivity with PET suggests bone scan can be eliminated from the staging evaluation at presentation. Due to its retrospective nature, the results of this study are subject to several forms of bias including selection bias, verification bias, test review bias, and incorporation bias. A prospective trial with appropriate verification of bony metastases is suggested to confirm the results.