A disposable access sheath having a deflectable tip is provided. The access sheath is very flexible and allows a physician or other medical professional to provide diagnostic or therapeutic services to a remote body cavity. The access sheath has a deflectable tip that is able to bend at least 90° or 180° or more. This flexibility allows the physician or medical professional to make a very tight turn to visualize or treat the body cavity being treated. The access sheath may include a visualization system, a working channel, an irrigation channel, or other desirable features. The access sheath may include an interface at the proximal end of the working channel for insertion of an instrument for diagnosis or treatment of a human or mammalian patient.