OBJECTIVE: To determine whether identity badges and lanyards worn by health care workers (HCWs) are capable of harbouring potentially pathogenic bacteria. DESIGN, SETTING AND PARTICIPANTS: Cross-sectional study of 71 HCWs (59 clinical ward staff and 12 infection control staff) at Monash Medical Centre, a university teaching hospital. Samples from lanyards, identity badge surfaces and connections (eg, clips, keys, pens) were cultured. The study was conducted from July to August 2006. MAIN OUTCOME MEASURES: Presence of pathogenic bacteria on identity badges and lanyards; differences in bacterial counts on items carried by nurses and doctors. RESULTS: A total of 27 lanyards were identified with pathogenic bacteria, compared with 18 badges. Analysing lanyards and badges as a combined group, seven had methicillin-resistant Staphylococcus aureus, 29 had methicillin-sensitive S. aureus (MSSA), four had Enterococcus spp and five had aerobic gram-negative bacilli. Lanyards were found to be contaminated with 10 times the median bacterial load per area sampled compared with identity badges. There were no significant differences between nurses and doctors in total median bacterial counts on items carried, but doctors had 4.41 times the risk of carrying MSSA on lanyards (95% CI, 1.14-13.75). CONCLUSION: Identity badges and lanyards worn by HCWs may be contaminated with pathogenic bacteria, which could be transmitted to patients. In view of this finding we suggest appropriate infection control interventions.