Tc-99m MIBI accumulation was seen in both tumor and atelectasis in two patients with central bronchogenic carcinoma and in one patient with atelectasis due to tuberculosis. These cases illustrate that Tc-99m MIBI also can accumulate in atelectasis caused by either benign or malignant lung lesions and that this accumulation may overestimate the extent of the tumor or may lead to a misdiagnosis. These potential pitfall should be considered in interpretation of Tc-99m MIBI scintigraphy in patients with lung cancer.