Sixteen skin biopsy specimens from early eruptive, evolving papules and well-developed plaques were obtained from eight patients with established atopic dermatitis. We found that the chronological and histopathological sequence begins with a perivascular interstitial spongiotic dermatitis, evolves into a psoriasiform microvesicular spongiotic dermatitis, which is sometimes focally lichenoid, and eventually concludes as a psoriasiform dermatitis. Thus, atopic dermatitis has characteristic and diagnostic histopathologic findings. These are portrayed and contrasted to what has been previously reported.