The methods of system reliability analysis represent an interesting set of tools used to follow the so-called "transfusion process", defined as all the steps from donors sensitization to recipients follow-up. FMECA, (Failure Mode Effects and Criticality Analysis), can be used as a prevention tool, independently of any dysfunction in the process. Of course, it can equally be used following a failure, in order to analyse the causes and to apply the specific corrections. Quality insurance, system reliability analysis, epidemiologic surveillance and safety monitoring operate in synergy. These three issues pertaining to transfusion safety constitute a dynamic system.