Cartilage invasion of laryngeal cancer has a significant impact on the choice of treatment modality and on the outcome for the patients. Cartilage invasion was evaluated radiologically and histopathologically in 18 patients who underwent total laryngectomy. The histopathological examination showed intracartilaginous tumor spread in nine specimens, whereas in the other nine no cartilage invasion was found. Magnetic resonance imaging (MRI) detected the cartilage invasion in six patients and excluded it in six. There were three false negative and three false positive findings from the MRI examination. The relatively common false findings of MRI should be kept in mind in the choice of treatment.