Giant cell tumor of the tendon sheath (GCTTS) is a slowly growing, benign soft tissue tumor. The tumors occur predominantly on the hands and feet. Although the clinical and histopathologic features are well-defined, only a few reports have described the cytologic appearance of this entity. A 26-year-old woman presented with a gradually developing circumscribed soft tissue mass near the proximal phalanx of her left little finger for one year. Imprint and fine needle aspiration (FNA) smears were obtained from the excisional biopsy specimen. The imprint smears were composed of predominantly singly dispersed bland mononuclear cells and several giant cells. The mononuclear cells were polygonal to round, and they showed a histiocyte-like appearance. Osteoclast-type multinucleated giant cells of various sizes were randomly scattered throughout the smears, and these cells contained 3 to 50 nuclei. Nuclear atypia and pleomorphism were absent in both the single and giant cells. Loose aggregates of hemosiderin-laden macrophages and binuclear stromal cells were also seen. The cytologic features of the FNA smears were similar with those of the imprint. Additionally, the FNA smears contained several clumps of densely collagenous stromal tissue that were seldom noted in previously reported cytologic material. The cytologic features were well-correlated with the concurrent histologic findings and the diagnosis of GCTTS was made. When the clinical and radiologic datas are integrated, the diagnosis of GCTTS can be strongly suggested, based on the pre-operative cytologic specimen.