Three cases of muscular metastasis as the first manifestation of malignancy are reported. These patients had no previous history of malignancy. All three were male. One had a single metastasis in the gluteus minimus muscle, and the other two had multiple metastases which were located in the adductor compartment of the thigh in one case and in the biceps brachii, quadriceps femori, and paraspinal muscles in the other. These metastases first manifested as a painful mass. The various imaging techniques (ultrasonography, computed tomography, and magnetic resonance imaging) determined the location and extension of the masses, although the images were nonspecific. The metastatic nature of the tumors was confirmed only upon histological studies. With reference to these three cases, features of muscular metastases are reviewed. The development of muscular metastases is an infrequent occurrence during the course of a cancer. The mechanisms which may explain the low incidence of muscular metastases are discussed.