Natural Killer (NK) cells have gained much attention as potential cells in antitumor immune defense mechanisms. In a group of 31 patients with surgically treated squamous cell laryngeal carcinoma, NK cell presence was semiquantitatively assessed by means of immunohistochemistry. A panel of three monoclonal antibodies including anti-CD16, was applied on frozen tissue sections. High CD 16+ cell presence was more frequently detected in poorly differentiated carcinomas (in 6 out of 14 cases) by comparison to carcinomas of high to moderate degrees of differentiation (in 1 out of 16 cases, p=0.031). No other clinicopathological variable appeared to influence NK cell presence in the examined specimens. No relation between NK cell detection and relapse-free survival emerged. Poorly differentiated laryngeal cancer cells appear to trigger off a greater NK cell tissue response than well and moderately differentiated cancer cells; however, the potential prognostic impact of this observation remains to be established.