Ragged, Ra, is a new semidominant coattexture mutant in the house mouse. Heterozygotes have a sparse coat in which the proportion of zigzag fibers is low; in agouti mice the coat is abnormally dark, especially on the dorsum. Most homozygotes show a generalized oedema and die soon after birth; the few survivors are naked. Ra is located at one end of linkage group V; it shows 24 percent recomhination with non agouti and 39 percent with pallid.