The Authors thorough analyse the subject of day-surgery underscoring the advantages this procedure represents in the light of the experience gained at "R.Elena" National Cancer Institute. The aims of ambulatorial surgery are, in broad terms, the safety of procedures, patients' compliance as well as organisational and economic savings for the health structure. In the future, one-day surgery might represent an important contribution to surgical therapeutical strategies allowing, if well organized, an excellent compromise between safety, convenience and reduced costs.