Cytologic features of a poorly differentiated "insular" carcinoma of the thyroid are presented. In fine needle aspiration cytology, the aspirates were highly cellular and tumor cells were arranged in loose cluster or singly dispersed on focally necrotic background. Occasional microfollicles were evident. The tumor cells had poorly defined, scanty cytoplasm and most of the nuclei were fairly uniform with coarse chromatin pattern. A few large pleomorphic cells were also noted. The cytologic findings of the present case were correlated well with the histologic findings, which showed typical insular pattern and the presence of uniform cells with occasional pleomorphism.