The hyoepiglottic ligament (HL) is a connective tissue structure that serves as the roof of both the paraglottic and the preepiglottic spaces and thereby anatomically separates the supraglottic larynx from the tongue base. Whole mount serially sectioned larynges with supraglottic cancer were reviewed to help clarify cephalad spread of cancer in this region. The whole mount slides were analyzed from 70 laryngectomy specimens that were resected for supraglottic cancer. The HL was breached by cancer in 13 specimens, and all of these displayed clinical and histopathologic invasion of the preepiglottic and paraglottic spaces. Invasion of the suprahyoid epiglottis was noted in 9 specimens, and invasion of the aryepiglottic fold in 4. There were no instances in which cancer escaped from the deep compartments of the supraglottic larynx to the tongue base without synchronous erosion of the suprahyoid epiglottis (insertion of the medial HL) or the pharyngoepiglottic fold (lateral HL). The HL is a resilient connective tissue barrier to the spread of cancer from the supraglottis to the tongue base. This investigation reinforced the concept that, typically, the HL acts as a deep cephalad surgical boundary in resecting supraglottic cancer that 1) is confined to the laryngeal membranes and 2) does not clinically invade the suprahyoid epiglottis.