Cystoscopy (si-ˈstäs-kə-pē) is endoscopy of the urinary bladder via the urethra. It is carried out with a cystoscope.

The urethra is the tube that carries urine from the bladder to the outside of the body. The cystoscope has lenses like a telescope or microscope. These lenses let the physician focus on the inner surfaces of the urinary tract. Some cystoscopes use optical fibres (flexible glass fibres) that carry an image from the tip of the instrument to a viewing piece at the other end. Cystoscopes range from pediatric to adult and from the thickness of a pencil up to approximately 9mm and have a light at the tip. Many cystoscopes have extra tubes to guide other instruments for surgical procedures to treat urinary problems.