Polyps of the intestines represent a considerable proportion of the practising pathologist's workload. There are many types of intestinal polyp and accurate histological assessment is imporant to ensure the accurate diagnosis and appropriate management of patients. Most polyps have a corresponding polyposis syndrome, the presence of multiple polyps. Some of these are well established and clearly defined in clinical, molecular and pathological terms, whilst other polyposis syndromes are less precisely characterized. The most important recent advances in our understanding of polyposis syndromes have come from molecular biological studies: these have considerable potential in the diagnosis and management of these syndromes. They also provide insights into the pathobiology of sporadic polyps and the pathogenesis of intestinal cancer.