OBJECTIVE: The current study sought to determine whether there were any significant cross-cultural differences in medical-physical findings, or in psychosocial, behavioral, vocational, and avocational functioning, for chronic low back pain patients. DESIGN: Partially double-blind controlled comparison of six different culture groups. SETTING: Subjects were selected from primarily ambulatory care facilities specializing in treating chronic pain patients. PATIENTS-SUBJECTS: Subjects consisted of 63 chronic low back pain patients and 63 healthy controls. Low back pain patients were randomly selected from six different culture groups (American, Japanese, Mexican, Colombian, Italian, and New Zealander). Ten to 11 were gathered per culture from a pool of patients treated at various pain treatment programs. Likewise, 10 or 11 control group subjects were obtained from each culture from a pool of healthy support staff. MAIN OUTCOME MEASURES: The Sickness Impact Profile and the Medical Examination and Diagnostic Information Coding System were used as primary outcome measures. RESULTS: Findings showed that (a) low back pain subjects across all cultures had significantly more medical-physical findings and more impairment on psychosocial, behavioral, vocational, and avocational measures than controls did; (b) Mexican and New Zealander low back pain subjects had significantly fewer physical findings than other low back pain groups did; (c) the American, New Zealander, and Italian low back pain patients reported significantly more impairment in psychosocial, recreational, and/or work areas, with the Americans the most dysfunctional; and (d) findings were not a function of working class, age, sex, pain intensity, pain duration, previous surgeries, or differences in medical-physical findings. CONCLUSIONS: It was concluded that there were important cross-cultural differences in chronic low back pain patients' self-perceived level of dysfunction, with the American patients clearly the most dysfunctional. Possible explanations included cross-cultural differences in social expectation; attention; legal-administrative requirements; financial gains; attitudes-expectations about usage, type, and availability of health care; and self-perceived ability and willingness to cope.