A case of intrasellar abscess simulating a pituitary tumor and whose etiologic diagnosis was made only by operation is reported. The possibility of the spreading of the infection from the pharyngeal cavum to the intra-craneal cavity, particularly to the sella turcica, through a non-obliterated craneum-pharyngeal canal, is admitted. After the operation (partial removal of the abscess capsule and aspiration of the pus) the neurological symptoms disappeared.