The authors report a new case of synovialo sarcoma of the laryngo-pharynx by optic and electron microscopy. Ultrastructural features were similar to those of joint synovialo-sarcoma, i-e, showing glandular like and spindle cell componments. Both of these shared several ultrastructural characteristics, favouring the hypothesis of a common origin. The site and the fine structure of this tumor are discussed according to the literature.