To determine the prognostic significance of depth of invasion in laryngeal cancer, the depth of invasion of tumor was measured with an ocular micrometer on the laryngectomy specimens of 94 surgically treated patients with T1, T2, and T3 laryngeal cancer and was expressed in millimeters. There was a significant negative correlation between the depth of invasion and disease-free survival. The tumors with no clinical involvement of regional lymph nodes in neck (NO neck) had significantly less depth of invasion than those with involvement (N+ neck). The tumors with pathologically confirmed cervical lymph node metastasis had significantly more depth of invasion than those without metastasis. For tumors with a depth of invasion equal to or greater than 3.25 mm, the rate of cervical metastasis in this study has always been significantly higher than for those with a depth of invasion less than 3.25 mm (P < .05). The mean depths of invasion for cases with and without recurrence were not significantly different. According to the multivariate analysis, depth of invasion (P = .047) and patient age (P = .113) significantly affected the disease-free survival independently. The depth of invasion did not significantly affect the recurrence and the interval between surgery and the development of recurrence (P > .15). The depth of invasion should be measured in every laryngectomy specimen. The depth of invasion influences the cervical metastasis and disease-free survival significantly but does not affect the recurrence rate. The depth of invasion plays an independent role in determining the disease-free survival.