The Pros and Cons of Cancer Registration E. Grundmann It may seem strange for somebody to hold a symposium on cancer regis tration and then submit a paper under the heading "The Pros and Cons of Cancer Registration." Indeed, this may be quite amazing to those of my colleagues who have been endeavoring for years or decades to provide a world-wide system of cancer registration. To be quite frank, this is exactly what I intended. Generally speaking, as scientists we are convinced that the work we do is worth while. We are in fact supported in this attitude by pub lic opinion, if one bears in mind that science is future-oriented. It may be said that science is a way for building the future, and that progressive-mindedness is - to use a modern word - "in." Never theless, we may somehow hesitate at this fashionable word. After all, science is not "in" in the way this word is interpreted by the younger generation. Indeed, this younger generation is much too sceptical whenever confronted with anything done by the older generation - and science is pursued primarily by the "establishment." Rather, it is "in" to criticize the system of society and, if possible, to overcome this system, which is responsible not only for many evils, but also for many illnesses.