Giant cell tumor(GCT) occurs very unusually in the rib(less than 1% of GCT). We present the cytologic features of GCT of the rib. It showed multiple cellular clusters composed of characteristic, benign looking osteoclast-like multinucleated giant cells and fibroblast-like mononuclear cells. The multinucleated giant cells contained numerous nuclei (average, 30 to 40 per cell, which were closely packed. The nuclei in giant cells were remarkably uniform and round to oval. The mononuclear, neoplastic stromal cells were elongated and spindle-shaped. There was no cytologically malignant portion in the tumor.