Born September 1, 1937, in Dresden, Gaehtgens studied medicine in Freiburg, Munich, and Cologne. After earning his license to practice medicine, he was hired as an academic assistant in Cologne in 1966 and completed his Habilitation in physiology in 1971. Gaehtgens accepted an appointment as professor at Freie Universität Berlin in 1983.

Gaehtgens has worked within various international academic and scientific societies and associations and has received a number of international awards and distinctions for his work.

Within the university’s academic self-administration, Gaehtgens served as vice president, becoming the dean of the School of Medicine of Freie Universität Berlin in 1995 and working as the executive vice president and deputy for the president of the university. Gaehtgens then went on to serve as president of Freie Universität Berlin from 1999 to 2003. In 2003, he was elected president of the German Rectors’ Conference (Hochschulrektorenkonferenz), a position he held until the end of 2005.