Intrinsic drug factors consist of all the properties of drugs that determine its clinical profile. There is usually a large amount of clinical data available at the moment of market introduction of a new drug. From these data a clinical profile can be composed, that makes it possible to compare the product with competitors. The product profile is the basis for important decisions concerning the marketing of the product. Frequently lacking is a demonstration of the relevance of the different drug attributes in therapeutical decision making. Prescriber scaling of intrinsic drug factors is introduced as a method for identifying the more important dimensions of a clinical product profile. If performed by medical experts the results provide important information that can be used to make predictions about market adoption of new products and to optimize marketing decisions in general.