In this article the structure of the diagnostical phase in the therapeutic process is described. A pleading is made in favour of a diagnostic phase that precedes and is not absolutely tied to the presuppositions of certain modern psychotherapeutic systems. Seven diagnostic sessions are described, in which one tries to get a picture of several aspects of the personality of the client and his social situation. Psychoanalytic theory is used to get a better view on the structure of symptoms. Also the 'libidinose Typen' of Freud are presented as a useful instrument in diagnosis. Certain types of symptoms and, hypothetically, certain therapeutic methods can be linked to the types. It is the opinion of the author that research in psychotherapy could be more accurate, if psychodiagnosis delivered more specific indications.