The formation of antigen-antibody precipitation bands in agar gel plates has become a standard immunological tool. The permanent recording of the band patterns would be ideally accomplished by securing a true photographic impression. Owing to the faintness of many of the bands and closeness of the bands to each other difficulties arise in attempting to obtain good photographic definition and resolution. An apparatus has been devised which achieves marked band definition and resolution and which, in its simplicity, reduces the photographing of gel plate precipitation patterns to an effortless routine. Excellent prints and lantern slides are readily obtained from negatives so produced. The apparatus and method are described in this article.