To improve quality of care, since 1989 the German Testicular Cancer Study Group (GTCSG) has published a series of guidelines on testicular germ cell cancer. These guidelines were updated in the 2007 publication"European Consensus on Diagnosis and Treatment of Germ Cell Cancer" (ECDTGCC). As an additional approach to improve the quality of care, the GTCSG established a national second-opinion system in 2006. The objective of this article is to summarise the present results, particularly regarding the interdependence between the guidelines and the second-opinion system.Data was exchanged between urologists and the second-opinion centres (SOCs) via the Internet. Data sets included the clinical primary data after orchiectomy, the intended therapy, the SOC's therapy recommendation, and the follow-up. The SOCs were 18 clinics that had qualified themselves through their participation in developing the ECDTGCC.From February 2006 to September 2008, 642 second opinions were requested. The discrepancy between the urologists' intended therapy and the SOCs' recommendations was 32.3%. The deviating second opinion in 40.3% (26.5%) of cases prevented overtreatment or undertreatment.Published guidelines are applied only sporadically. The results of the SOC system show that on the basis of this system, guidelines can be better implemented; in turn, the discrepancy between evidence-based guidelines and the actual treatment administered can be diminished.