BACKGROUND Studies have shown that women use more health care services than men. We used important independent variables, such as patient sociodemographics and health status, to investigate gender differences in the use and costs of these services.   
 METHODS New adult patients (N = 509) were randomly assigned to primary care physicians at a university medical center. Their use of health care services and associated charges were monitored for 1 year of care. Self-reported health status was measured using the Medical Outcomes Study Short Form-36 (SF-36). We controlled for health status, sociodemographic information, and primary care physician specialty in the statistical analyses.   
 RESULTS Women had significantly lower self-reported health status and lower mean education and income than men. Women had a significantly higher mean number of visits to their primary care clinic and diagnostic services than men. Mean charges for primary care, specialty care, emergency treatment, diagnostic services, and annual total charges were all significantly higher for women than men; however, there were no differences for mean hospitalizations or hospital charges. After controlling for health status, sociodemographics, and clinic assignment, women still had higher medical charges for all categories of charges except hospitalizations.   
 CONCLUSIONS Women have higher medical care service utilization and higher associated charges than men. Although the appropriateness of these differences was not determined, these findings have implications for health care.
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