Cytologic smear preparations of fine needle aspirates obtained from 71 patients with biopsy-proven metastatic malignant melanoma were morphologically analyzed. Cell diameter, percentage of cells lying individually, smear cellularity, mitotic rate, percentage of cells with nuclear inclusions and number of giant cells were quantitated. Qualitative estimates of degree of pigmentation, background composition, presence of macrophages, presence of contaminating blood, cell shape, amount and appearance of cytoplasm, prominence of Golgi apparatus, reactivity with the antibody NKI/C-3 and eccentricity of the nuclei were made. While eccentric nuclei, cytoplasmic vacuoles, intranuclear inclusions, high cellularity and cells with abundant cytoplasm were found frequently in smears from malignant melanomas, the presence of reactivity with NKI/C-3, pigment, giant cells, a bloody background and a lack of cell cohesion were the features most commonly associated with smears obtained from patients harboring metastatic melanoma.