In this article some problems about nursing theories are discussed. It is presumed that a science does not turn into a nursing science because it deals with nursing practice. Crucial is the way in which the practice is viewed, i.e. the question which theory is the starting point. Even normative nursing theories must be tested out in reality though this verification cannot be made exclusively with the methods of logical empiricism. The obligation for nursing theories to fit the metaparadigm as well as the concept of metaparadigm are discussed. It is also stated that nursing theories do not correspond to the diversity of everyday nursing. In order to create a complex everyday live, grounded theories are needed. For a better understanding, two grounded theories are described.