Chronic diarrhea is a common problem in cats. Inflammatory bowel disease and lymphoma are frequently identified causes. Intestinal biopsies are required to differentiate these conditions. Biopsies can be obtained through an endoscope passed into the intestinal tract but only superficial biopsies can be obtained by this method and relevant tissues required for diagnosis may be missed. This study will compare the value of the less invasive technique of endoscopic biopsy to exploratory surgery and biopsy for the diagnosis of common intestinal diseases.