The focus of this paper is to describe the development and fabrication of a portable hand-held electronic area planimeter to measure wheal areas during dermatitis assays. The planimeter straddles over the wheal and the scientist traces the wheal's perimeter using an optical beam splitter/cross-hair and a miniature x-y table. Transducers connected to the x-y table and an electronic circuit performs the area integration and displays the data on a digital panel meter. The apparatus permits noncontact measurement of areas up to 1000 mm2 with a resolution of 1 mm2.