Alcohol is the most used disinfectant in GMP cleanrooms. Alcohol's most appreciated features, the almost total absence of residues and its detergent action, depend on its quick evaporation. This means that a short contact time should be considered as a effectiveness limiting factor. Even if GMP guidelines clearly request a specific detergent step before disinfection, IPA is widely used both as cleaner and disinfectant for critical surfaces in aseptic areas, too. What should be considered to define the surface bioburden safe level ? How can it be met? We discuss the benefits and limits of the most commonly used disinfectants in GMP critical surfaces routine decontamination procedures, with particular focus on alcohol. Then, we point out the importance of mechanical actions for detergency and how disinfectants validation studies critical parameters have to be defined.