This paper reports the results of the information retrieval project PADOK‐II. This project, which began in November 1987, is being carried out by the Linguistic Information Science Group of the University of Regensburg (LIR) in cooperation with the German Patent Office (GPO) and is sponsored by the German Ministry for Research and Technology. The long‐term aim is to integrate artificial intelligence into information retrieval research without neglecting traditional information retrieval methodology. In PADOK‐II an information retrieval system is considered which indexes documents rather shallowly using free‐text or morphological components. A large‐scale retrieval test has been carried out, based on the German Patent Information System. Answers have been obtained to some 400 queries made by 10 users in simulated real‐life situations. These results have been used to attempt to answer the question: ‘How do the linguistically‐based functions of an indexing system contribute to its performance?’ As a spinoff of this test, the influence of document size and structure was studied with a view to identifying the most reasonable basic content for a German Patent Information System.