PURPOSE: Core and optional courses of study in complementary and alternative medicine (CAM) are being incorporated into medical curricula. The authors carried out this study to validate a tool to examine students' attitudes toward holism and CAM and explore the relationships between their attitudes and other demographic and education-related characteristics in a large, multischool, international sample of medical students. METHOD: In 2003 the authors used a modified version of the Integrated Medicine Attitude Questionnaire (IMAQ) to survey students at a total of six medical schools in the United Kingdom, New Zealand, Canada, the United States, and Hong Kong, China. A three-factor model was tested using confirmatory factor analysis, and the internal consistency of the factors were identified using Cronbach's alpha coefficients. A multiple-indicator multiple-cause (MIMIC) analysis was carried out to determine the relationship between IMAQ factors and student characteristics. RESULTS: The authors validated a three-factor model for the IMAQ: (1) attitudes toward holism, (2) attitudes toward the effectiveness of CAM, and (3) attitudes toward introspection and the doctor-patient relationship. Cronbach's alpha coefficients ranged from .41 to .71. The MIMIC model indicated that various background variables were associated with IMAQ factors (gender, race/ethnicity, and school), depending on whether students had previously visited a CAM practitioner and whether students were willing to undertake a special study module in CAM. CONCLUSIONS: Further development work on the IMAQ is required and qualitative research to verify and examine the reasons behind the relationships found in this study between students' attitudes to holism and their demographic and education-related characteristics.