Objectives: The aims of this study were to articulate what measurement equivalence/invariance (ME/I) is, determine its impact, describe the procedural techniques in conducting ME/I, review the health-care literature on the climate and culture of patient safety, and discuss questions about ME/I testing. Methods: We looked at English language journal articles published between Jan 2000 and April 2010 by searching PubMed (free Medline) electronic databases using the keywords ”patient safety attitude” or ”safety climate” or ”safety culture”, simultaneously with the terms ”health care” or ”hospital” in title/abstracts, and ”safety instruments” in text. Our focus was on quantitative empirical studies adopting questionnaire-survey methods. A total of 41 articles were reviewed to analyze the psychometric properties of instruments, the level of analysis and the use of this measure for comparisons. Results: We found that most studies demonstrated reliability and validity of the constructs using the statistical methods of reliability estimation, correlation, regression, exploratory factor analysis, confirmatory factor analysis, and multitrait-multimethod matrices, and tested group differences by t-tests, ANOVA or MANOVA. Evaluations of invariant factor structure across populations or contexts by applying ME/I testing were seldom addressed. The majority of these studies did not address the ME/I issue. We suggest that some analytical forms of ME/I testing, the triggers for not supporting ME/I, and the remedies for patient safety require further research. Conclusions: There are some questions about the sensitivity of ME/I analytical procedures and the susceptibility of these procedures to contextual influences.