The design, construction, and evaluation of an internally worn laryngeal prosthesis for laryngectomized patients is presented. Existing speech rehabilitation techniques were analyzed. The reed-fistula technique was adopted as having the most potential for effective design improvement. Its deficiencies were explored, and an alternative strategy for an internal prosthesis was formulated. Prosthetic mechanisms which met the design criteria were developed, and their performance was evaluated bothin vitroandin vivo.In this modified technique, the prosthesis is worm internally at the end of a surgically constructed fistula leading to the base of the patient's vocal tract. Exhaled air powers a miniature vibratory mechanism, whose output enters the vocal tract directly and supplies both a voiced and a voiceless sould source. Two patients using the new mechanism have regained a reasonable, usable speech with a minimum amount of effort and practice. An intelligibility test rated one patient's speech clearly superior over electronic and conventional reed-fistula speech.