The three-dimensional organization of lens fibers in the Rhesus monkey was studied by means of scanning electron microscopy. The mutual anchoring of lens fibers is brought about by three types of interlocking devices: (1) interlocking protrusions on the apical and lateral edges, (2) ball-and-socket junctions on the apical and lateral surfaces, and (3) microplicae or tongues and grooves on the apical and lateral surfaces. Interlocking protrusions are present all over the lens, whereas ball-and-socket junctions and microplicae are restricted to cortical and nuclear regions, respectively. The distinction between interlocking protrusions and ball-and-socket junctions is discussed in detail.