It is well known that fine needle aspiration biopsy(FNAB) is very useful and has a high accuracy rate in the diagnosis of renal neoplasms. Although there is some indecision to perform the FNAB for a rare possibility of tumor seeding along the biopsy needle tract, it tends to be used increasingly. As in the cytologic diagnosis of metastatic lesion through-out the body, renal cell carcinoma should nearly always be considered in the differential diagnosis, the precise understanding of cytologic features of renal cell carcinoma with various cell types and architectural patterns is necessarily required. In this report, we present three cases of primary renal cell tumors, two of renal cell carcinomas and one of oncocytoma, preponderantly emphasizing the cytologic differential points in the FNAB specimen.