The significant progress made in the understanding of the behaviour of geomaterials would not have been possible without the use of numerical methods. In particular, developments in constitutive modelling are closely related to advances made in the field of numerical analysis and therefore finite element (and other) methods have had a significant impact on geotechnical research since the 1970s. Advances in computer hardware and, more importantly, in geotechnical software over the past ten years have resulted in a widespread application also in practical geotechnical engineering. These developments enable the geotechnical engineer to perform very advanced numerical analyses at low cost and with relatively little computational effort. Commercial codes, fully integrated into the PC-environment, have become so user-friendly that little training is required for operating the programme. They offer sophisticated types of analysis, such as fully coupled consolidation analysis with elasto-plastic material models. However, for performing such complex calculations and obtaining sensible results a strong background in numerical methods, mechanics and, last but not least, theoretical soil mechanics is essential. Discrepancies in results are therefore often observed when a particular problem is solved utilizing different codes or when various users with different theoretical and practical background tackle the problem. This has been shown by several benchmark exercises performed by the Working Group 1.6 of the German Society of Geotechnics and Working Group A of the COST ACTION C7.