The purpose of this manual is to define a limited number of indicators that will objectively describe the management and use of antimicrobials in hospitals and to provide tools and step-by-step instructions for designing and carrying out an assessment of antibiotic use and management in hospitals. The indicators in this manual will complement the existing WHO (1993) indicators of outpatient antimicrobial use suggested in How to Investigate Drug Use in Health Facilities (including percentage of encounters in which an antibiotic was prescribed and percentage of medicine costs spent on antibiotics) and will address the need for antimicrobial indicators for inpatient conditions.