Objective: To review evidence of the effectiveness of information technology (IT) interventions to improve antimicrobial prescribing in hospitals. Method: MEDLINE (1950-March 2015), EMBASE (1947-March 2015) and PubMED (1966-March 2015) were searched for studies where an IT intervention involving any device (e.g. computer, mobile phone) was evaluated in practice. All papers were assessed for quality using a 10-point rating scale. Results: We identified 45 articles that evaluated an IT intervention to improve antimicrobial prescribing in hospitals. IT interventions took four main forms: (1) stand-alone computerized decision support systems (CDSSs), (2) decision support embedded within a hospital's electronic medical record (EMR) or computerized provider order entry (CPOE) system, (3) computerized antimicrobial approval systems (cAAS), and (4) surveillance systems (SSs). Results reported allowed us to perform meta-analyses for three outcome measures: appropriate use of antimicrobials, patient mortality and hospital length of stay (LOS). IT interventions increased appropriate use of antimicrobials (pooled RR: 1.49, 95%CI: 1.07-2.08); however no evidence of an effect was found when analysis included only studies with a quality score of five or above on the 10-point quality scale (pooled RR: 1.53, 95%CI: 0.96-2.44). There was little evidence of an effect of IT interventions on patient mortality or LOS. The range of study designs and outcome measures prevented meaningful comparisons between different IT intervention types to be made. Conclusion: IT interventions can improve the appropriateness of antimicrobial prescribing. However, high quality, systematic multi-site comparative studies are critically needed to assist organizations in making informed decisions about the most effective IT interventions.