In psoriasis changes of the DHEA metabolism could be demonstrated. These genetically determined basic alterations may represent an important factor for the manifestation of psoriasis. They consist of a decreased penetration of DHEA through the cell membrane and an increased reduction of DHEA to ADIOL, leading to a reduced DHEA/ADIOL ratio. In the present investigations the question was whether the assay of these parameters may aid in the detection of latent psoriasis. For this purpose 31 members form 6 unselected families of psoriatics (8 manifested psoriatics, 18 potential psoriatics, 5 clinically and anamnestically healthy family members by marriage) as well as 6 further controls were examined. It could be shown that those changes in the DHEA metabolism, which are evident in manifested psoriatics also occur at least in part of potential psoriatics. However, both parameters investigated do not always behave the same way. Hence, from the present data a satisfactory diagnosis of latent psoriasis does not seem possible. Still, the estimation of the above parameters may aid in the attempts to define latent psoriasis. Further investigations of such families are warranted for final elucidation of this problem.