Technetium-99m tetrofosmin and thallium-201 lung SPECT imaging were performed in a patient with adenocarcinoma of the lung. Significant activities in the lung lesion were clearly depicted on both technetium-99m tetrofosmin and thallium-201 SPECT imaging. The early uptake, delayed uptake ratios and retention indices of the tumor were 2.75, 2.39 and -1.31 for thallium-201 imaging and 3.09, 2.27 and -26.5 for technetium-99m tetrofosmin imaging, respectively. This preliminary report suggests that technetium-99m tetrofosmin may have potential as a tumor imaging agent.