Lymphocytic colitis and collagenous colitis are two histologic forms of microscopic colitis, a condition which was fi rst recognized over 30 years ago. It is often found in adults with chronic, watery diarrhea although endoscopic examination of the colon is frequently normal. The diagnosis is based on microscopic examination of colonic biopsies. The aim of this review is to familiarize general surgical pathologists with the morphologic features of lymphocytic and collagenous colitis. In additional, this review emphasizes good communication with the endoscopist to allow correct recognition and ensure appropriate treatment.