This document provides guidance for the selection, use and interpretation of results from application of biological indicators when used in the development, validation and routine monitoring of sterilization processes.It does not consider those processes that rely solely on physical removal of microorganisms, e.g. filtration.It is not applicable to combination processes using, for example, washer-disinfectors or flushing and steaming of pipelines.It does not specify requirements for the selection and use of biological indicators intended to monitor vaporised hydrogen peroxide processes for isolator and room biodecontamination processes at atmospheric pressure.It is not applicable to liquid immersion sterilization processes.