We describe a case of aggressive fibromatosis of the larynx occurring in a 75-year-old man. The lesion manifested with voice hoarseness and swallowing difficulty. A computerized tomographic scan of the neck revealed distortion of the glottic profile. A malignant tumor was suspected. Although a laryngoscopy-driven biopsy was non-diagnostic, total laryngectomy was done, since the lesion was not deemed amenable to conservative therapy. Grossly, the glottic rim was infiltrated by a hard, grey-white tissue showing a tentacular outline. Tissue sections featured a moderately cellular lesion composed of spindle cells with bland, tapered nuclei, enmeshed in a variably collagenized ground substance. Delicate spindle cell fascicles surrounded the native submucosal seromucous glands and had invaded the thyroid cartilage and the thyroid gland as well. The spindle cells were immunopositive for actins and vimentin, and negative for keratins, epithelial membrane antigen, desmin, and S-100 protein. No further therapy was administered. Periodic follow-up visits were negative. The patient died 5 years after surgery of myocardial infarction with no clinical evidence of lesion recurrence. Based on the available literature, our data confirm that laryngeal fibromatosis in adult patients is a locally infiltrating and progressive disease. Total laryngectomy with clear margins is needed as to avoid the high risk of local recurrence.