A surgical helmet system (SHS) is either a loose-fitting hood or a hood combined with an integral gown (called a toga system). SHSs are used during orthopedic procedures to decrease the patient's risk of deep wound infection by keeping skin and other particles from the surgeon's face from falling into the open surgical site. They are also used to protect surgical staff from infectious blood splashes and potentially infectious aerosols generated by power tools during orthopedic procedures - and it is this aspect of SHS use that has attracted particular attention, given the intensified interest in healthcare worker (HCW) protection (e.g., against human immunodeficiency virus [HIV], tuberculosis [TB], and hepatitis C virus [HCV]) in hospitals today. Ironically, the very factors that have led to SHSs' recent popularity may limit the need for their use, inasmuch as facilities have instituted so many other effective infection control methods against bloodborne and airborne pathogens. Although SHSs do provide splash protection against bloodborne pathogens, institutions may already by adequately protecting their staff against this hazard. In addition, they may be using SHSs to provide other types of patient and HCW protection that are already being provided by existing infection control measures. SHSs are available in a wide variety of configurations. We evaluated a total of six SHSs: one hood and one toga system each from three manufacturers. The units we tested were among each manufacturer's bestselling systems. We examined how well they would protect patients against deep wound infections and HCWs against splashes and aerosolized particles. We also evaluated their comfort and ease of use for wearers. We found that all of the SHSs provided sufficient patient protection against particles shed by the surgeon. We also found that the hood-only units and the hood components of the toga units provided sufficient HCW splash protection. (The gown portion of the toga systems failed our fluid-resistance criterion. However, we did not test the separate surgical gowns that are used with the hood-only units, and we do not know if they provide any greater level of protection than the toga fabric does). We rated all hood-only units Acceptable. We rated all toga units Acceptable-Not Recommended because the level of patient and HCW protection provided by the toga systems did not justify their significantly higher cost. We did find differences in the level of HCW respiratory protection these systems provided against aerosols. However, we do not believe that this should be a significant selection consideration because there is no established need for respiratory protection during orthopedic procedures. (Respiratory protection is needed against TB aerosols, but hip and knee arthroplasty procedures are usually elective and would be delayed on any active or suspected TB patient until the patient is noninfectious). To establish the context for this study, we first present a Guidance Section, "Do You Need Surgical Helmet Systems for Orthopedic Procedures?" In this section, we discuss the infection risks present during orthopedic procedures. We also outline the protective measures that institutions may already have in place to reduce these risks. We then discuss how SHSs fit into the infection control picture. Supplementary material in this section includes a discussion of the respiratory protection needed against Mycobacterium tuberculosis and a table of factors affecting the choice among SHSs, respirator masks, and surgical masks for patient and HCW protection. Ultimately, the choice to use SHSs may be dictated by the training and preference of the surgical staff. But this Evaluation will help facilities to (1) make this decision and, if appropriate, (2) select the best system for their needs...