In this paper the process of ageing of fingerprints is considered and such factors affecting the process as: chemical composition of a fingerprint trace, external influences and background material are taken into account. On the basis of experience accumulated over a long period of time standards have been set allowing the determination of the time span during which traces of different chemical compositions stored in various ambient conditions can be effectively used for dactyloscopic purposes. In the closing part of the paper the efficiency of the method and usefulness of the results obtained are presented. © 1990.