Conference reports of scientific meetings do not automatically justi fy publication. Our decision to publish the Proceedings of this Sym posium was based on a number of reasons. The subject of more or less grave adverse side-effects of oral contra ception is of major importance for all women. If the research insti tutions of Gynecology make fundamental mistakes in this subject, then the trust in them will diminish substantially. National institutions will have to shoulder a part of that burden, too, if they do not suc ceed in timely prevention of grave and widespread health risks and damages. Adverse side-effects of oral contraception become only apparent in later life and probably only after a latent interval of at least 10 years. The German female population will be fully exposed to that situation during the next decade. Up to now about 40 % of the women aged 35 years or older have no experience with the pill. Ten years later nearly all of them shall have used the pill for a short period at least. If serious long-term side-effects exist, we have to build up our research strategy now to detect these health hazards in time. Large-scale studies cannot be generated just out of nothing, the development and review of ideas in a pilot phase is necessary. The pilot phase of a German long-term study began three years ago. We shall report our experiences of that pilot phase, because this might be of value for other projects of this kind.