The purpose of this study is to investigate the role of 123I-Tyr-3-octreotide scintigraphy in staging small-cell lung cancer (SCLC), its efficacy for the discrimination of limited and extensive disease stages and its regional sensitivity for different metastatic locations. Twenty patients with histologically confirmed SCLC and 50 radiologically staged tumors sites were investigated by an imaging protocol including dynamic (0-30 min p.i.), static (30 min, 90 min, 4 hr, 24 hr p.i.) and SPECT (90 min p.i.) studies. The primary tumor site was visualized in 84%, whereas the best delineation was noted in early planar (15-30 min p.i.) and SPECT studies, due to a rapidly decreasing tumor-to-background ratio. Lymph node metastases were seen in 73%, but SPECT was needed for anatomical localization. All three adrenal metastases could be identified in sequential planar images. One clinically unsuspected brain metastasis was seen, whereas a second clinically overt metastasis was not visualized. The global and regional sensitivity for liver and bone metastases was unsatisfactory. In summary, 78% (7/9) of the patients with extensive disease were correctly identified by scintigraphy alone. We conclude that 123I-Tyr-3-octreotide scintigraphy is a substantial tool in the staging work-up of SCLC if it is performed initially to allow fast identification of patients with extensive disease stages and save additional radiological or invasive examinations. Yet, 123I-Tyr-3-octreotide scintigraphy cannot substitute liver sonography or conventional bone scanning in patients who have no scintigraphic evidence of distant tumor spread.