Abnormal accumulation of Tc-99m MDP in two metastatic lesions of the liver was observed in a patient with resected colon carcinoma. Single-photon emission computed tomography (SPECT) revealed characteristic marginal accumulation of Tc-99m MDP in both of those metastatic lesions. X-ray CT showed the corresponding marginal calcification in one of the metastases, but no apparent calcification was observed in the other lesion. Two months later, however, the latter also became calcified on x-ray CT. These findings suggest that the accumulation of Tc-99m MDP in the present case is strongly related to the calcium deposition and that Tc-99m MDP may accumulate in a calcified metastatic lesion before the calcification appears on x-ray CT.