Two patients, members of one family, with Peutz-Jeghers syndrome are described who underwent surgery for bowel obstruction. Both had multiple polyps in the gastrointestinal tract. Severe dysplasia and adenomatous change were present in two hamartomatous polyps adjacent to a stenosing colonic carcinoma in one patient and moderate dysplasia and adenomatous change were observed in two hamartomatous rectal polyps in his son. These changes support recent reports in the literature of progression towards neoplasia in these lesions.