[The importance of biological standardization in clinical laboratory examinations (author's transl)]

The AA. consider the various causes that can give rise to different results regarding one same biological sample which has been examined various times in the same or in different laboratories. From the analysis of the possible sources of variability and from the results obtained in research performed by various laboratories in the course of a polycentric co-ordinate study, the AA. deduce some general considerations about the measures to be taken in order to reduce the different sources of variability (either fortuitous or systematic) and they especially emphasize the practic usefulness of considering the question of "laboratory errors" not only as a question of accurate dosage, but also, and primarily, as a question of biological standardization.