The invention relates to polypeptides specifically binding to CD38 and are therefore suitable for the diagnosis and for the therapeutic and prophylactic treatment of diseases which are characterized by increased CD38 expression. Conjugates and pharmaceutical compositions comprising the polypeptides are disclosed as well. In addition, the invention relates to the use of such polypeptides in methods for the detection of CD38 and / or CD38-expressing cells in a biological sample. A process for the purification and concentration of CD38 and / or CD38-expressing cells in which the antigen-binding polypeptides are used are also described.
