Smyth line (SL) chickens develop a spontaneous, autoimmune loss of melanocytes (vitiligo) from the feather. To determine whether lymphocyte infiltration into two-week-old regenerating feathers of vitiliginous chickens was accompanied by lymphocyte infiltration into the skin, skin biopsies were conducted in SL chickens at two-week intervals throughout the development of vitiligo (SLV) when the chicks were 6 to 14 weeks of age. Control skin samples were obtained from age-matched, normally-pigmented Light Brown Leghorn (LBL) chickens. Frozen skin sections were labelled with a panel of mouse mAb to identify various lymphocyte populations. There was no lymphocyte infiltration into the skin of SL or control chickens. However, in both lines of chickens, dermal lymphoid aggregates (DLA), consisting primarily of T cells, were observed. In the DLA of SL chickens, the ratio between CD4+ and CD8+ T cells was lower (P = 0.005) and the percentage of gamma delta T cells higher (P = 0.027) than in the controls. Additionally, in SL chickens the lymphocyte populations in the DLA varied depending on the developmental stage of vitiligo. These data suggest a relationship between the DLA and autoimmune vitiligo in the SL model.