The Dundee experimental bald rat (DEBR) is reported as a model for human alopecia areata. Parallels with human alopecia areata were observed in relation to the gradual and patchy loss of hair and the penetration of both pelage and vibrissa follicles by mononuclear cells. In particular, the apparent disruption of the follicles within the precortical region of the epidermal component and consequent alterations of normal geometrical relationships between dermal and epidermal components relate directly to similar studies on human alopecia areata. In comparison with other previously described hypotrichotic rodent mutants, the DEBR rat exhibits a unique mechanism of hair loss which may provide important information regarding the pathomechanism of human alopecia areata.