The Collaborative Transplant Study originated from the need to gain further insight into the complex problems and risks involved in human organ transplantation. It is based on the voluntary cooperation of transplant centers from around the world. The study was initiated in 1982 by Gerhard Opelz in Heidelberg. After his retirement at the end of February 2015, Caner Süsal took over its coordination. Gerhard Opelz is however still involved as an advisor and supports the staff in Heidelberg.

The study's aims are strictly scientific. The philosophy behind it is that the knowledge-gaining process can be accelerated by combining the experience of many, especially with respect to complex interactions of factors and the analysis of rare events. Aside from maintaining a transplant registry, the CTS conducts various prospective and retrospective studies on particular research topics.


With the active support of more than 400 transplant centers in 42 countries, the CTS is the largest international voluntary study in the field of medicine. More than 500,000 data sets for kidney, heart, lung, liver, and pancreas transplants have been collected. This wealth of data has provided invaluable insights into transplantation-related problems.

The study is coordinated from the Institute of Immunology of the University of Heidelberg, Germany. The Heidelberg CTS team includes physicians, immunologists, computer scientists, statisticians and laboratory staff.

Research Topics

Research topics within the CTS project include:


Results are reported in the periodic CTS Newsletters and in scientific publications. As a feature of the website we are providing a collection of graphs showing analysis results based on subsets of CTS data. This collection of graphs will continue to be extended.

If you have any questions concerning the CTS or this web server please feel free to contact us.