Quality management in internal medicine and surgery is especially difficult because of the magnitude of these two subjects. Between the years 1994 and 1996, the German scientific societies of internal medicine developed the manual "Rationelle Diagnostik und Therapie in der Inneren Medizin". The cooperation of colleagues was most helpful when the interests of several internal branches were involved. An even greater challenge is the development of interdisciplinary internal and surgical guidelines, which are presented here for cholelithiasis.