Abstract: A caliper which is especially constructed for measuring the length, width, area and/or volume of living parts of mammals during surgery, without injuring the parts, particularly inside a body cavity is described. The caliper includes a pair of long straight arms which are approximately parallel in a closed position and which pivot apart in a scissors movement in order to position the body part between the distal ends of each of the arms used for measuring. The other ends of the arms are connected to a pivot means and to a handle provided by extensions from the arms and the pivot means. Adjacent the distal ends of the arms, precisely measured and spaced apart reflecting means, such as ridges or grooves, are provided which reflect a surgery light when the arms are inside the body cavity and preferably having contrasting colored shiny tips at the distal ends.