To shorten the length of stay before the surgical intervention and to increase the performance of the elective surgery, the Ospedale Maggiore di Milano decided to open a preadmission service working as a day hospital setting. This service has to evaluate patients eligible for surgery both from the surgical than for the anesthesiological point of view. The study wants to state the efficacy, the performance, the quality of this service with particular attention on the elaboration of diagnostic protocols. In this study were investigated more than 8.000 accesses registered in two years (2003-2004) from 9 units of surgery. The evaluation wants to improve the level of quality of this structure in order to better identify the anesthesiological patient risk, the diagnostic protocols and the coordination with all the ancillary services in the hospital.