Concept and basic routines of a new program package (KINPAK) for standardized evaluation of kinetic parameters are described. This new program is not based on compartmental analysis. Instead the experimental data sequence is fitted by flexible regression functions adequate for concentration-time curves. From fitted regression curves the relevant biologic parameters are calculated. These parameters express mainly the geometric properties of the curve. The fitting and parameter calculation is governed by numerous plausibility checks which guarantee feasible and reproducible results without arbitary intervention by the user. The program is mainly designed for use in industrial research and for presentation to administrative authorities. The methods are standardized and concieved to be performed as closed job. Tables and graphs can be generated for entire experimental series and are ready for use as documentation required by regulatory agencies.