The purpose of this research is to identify and formalize the Hospital Hygiene Service activities and products, evaluating them in a cost accounting management view. The ultimate aim, is to evaluate the financial adverse events prevention impact, in an Hospital Hygiene Service management. A three step methodology based on affinity grouping activities, was employed. This methodology led us to identify 4 action areas, with 23 related productive processes, and 86 available safety packages. Owing to this new methodology, we was able to implement a systematic evaluation of the furnished services.