Familial adenomatous polyposis (FAP) is one of the most common hereditary syndromes associated with an increased risk of colorectal cancer. Onset of polyp formation and cancer in childhood is very unusual but has recently been associated with a specific mutation at codon 1309 in exon 15 where a more severe phenotype is sometimes observed .We report a 12-year-old girl who presented with haematochezia. The girl’s mother and aunt had died of colon cancer which developed from untreated FAP. The other two aunts also had FAP and underwent colectomy. Endoscopy showed extensive polyps presented on the luminal surface of the entire colon. Histomorphology confirmed a low grade of intraepithelial neoplasia (IEN) in three polyps and the patient underwent colectomy. We present a review of the literature focussed on early onset of IEN in polyps in children with FAP. Clinicians should take note of the family history and be prepared to consider much earlier intervention if symptoms occur in a child with a family history of FAP.