1. Pelvic surgery for hysterectomy and cystectomy is associated with distal large bowel and anal dysfunction related to pelvic denervation which is also investigated in spinal cord injury employing physiological studies of the sigmoid colon and anal canal. 2. Radiotherapy used for treatment of prostate cancer can cause damage to the rectum and anal sphincter mechanism resulting in bowel dysfunction and incontinence although conformal radiotherapy has reduced the incidence of this complication. The incidence and mechanism of injury is investigated by anorectal physiological studies to determine rectal and anal function before and after treatment. 3. Anal Intra-epithelial Neoplasia is increasing in incidence among the homosexual population and immunocompromised patients. The pattern and progression of the disease in this population is observed, to determine an opitmal surveillance policy. Experimental work using 5-Aminolevulinic Acid, has demonstrated selective uptake of the dye in AIN3 provididng a conduit for treatment with Photodynamic Therapy. 4. Anal cancer is increasing in incidence. Chemoradiotherapy is the first line of treatment. Defining the radiation field influences the outcome particularly with respect to local lymphatic spread. This place of sentinel node biopsy identified by patent blue dye, radioisotope and supermagnetic iron oxide is investigated and the role of CT PET scan is explored. 4. MRI is less invasive than other imaging modalities in the diagnosis of inflammatory bowel disease and its potential role is investigated in measuring the severity of the disease, comparing radiological with pathological parameters.