We investigated which diagnostic procedures are mandatory for all transplant candidates irrespective of their individual situation in European transplant centres, how homogeneously these are applied and what centre characteristics determine differences in the diagnostic approach. A questionnaire was sent to European renal transplant centres asking which of 45 listed diagnostic procedures are mandatory for every transplant candidate. The 154 participating centres require 15.6 +/- 5.6 (4-33) mandatory tests, with significantly less mandatory diagnostics in centres in the UK (8.5 +/- 3.9) and Scandinavia (9.8 +/- 2.3). Geographic location is the single significant factor in multifactorial analysis of possibly related factors. Detailed analysis revealed 16 tests that are required significantly less often in the north of Europe. There are significant differences in the evaluation of renal transplant candidates across Europe. In some parts of Europe transplant candidates are either investigated more discriminately or less comprehensively than in other regions.