The present study was purposed to evaluate the incidence and the characteristics of metastatic "cold" lesions in Tc-99m-MDP bone scans of adult patients with solid malignancies. There were 29 cold lesions in 24 patients. The incidence of cold lesions was about 1% of total cases of bone scans for the patients with malignancy, or 2.5% of cases with bone metastases, The primary sites of malignancies were lung (four cases), uterine cervix (three cases), kidney, nasopharynx, thyroid, urinary bladder, prostate, lymphoma(two cases each other), liver, breast and others (one case each other). But the relative incidence of cold lesion in lung cancer and breast cancer was low. The most frequent site of cold lesion was spine and pelvis, skull and rib were followed. The incidence of cold lesion was related to the regional incidence of bone metastases. The size of the cold lesions was greater than that of the hot. There were six cases of single cold lesion without any other abnormalities and two cases of cold lesion which were initially hot. So it should be considered that bone metastases might be presented as cold lesions in bone scan.