A 2002 evaluation of the National Centers of Excellence in Women's Health (CoE) provided evidence that women receive higher-quality primary health care, as indicated by receipt of recommended preventive care and patient satisfaction, when they receive their care in comprehensive women's health centers. A potential rival explanation for the CoE evaluation findings, however, is that the higher quality of care in the CoE may be attributable to a predominance of female physicians in CoE settings. More women who receive health care in a CoE have a female regular physician and female physicians may provide more preventive health services. Additionally, women may self-select into the CoE because of their preference for female providers. This paper presents results of an analysis examining the role of physician gender in the CoE evaluation. Women seen in three CoE clinics and women seen in other settings in the same communities who had a female physician are compared to assess the CoE effect while controlled for physician gender. The findings confirm a positive CoE effect for many of the quality of care indicators that were observed in the original evaluation. Women seen in CoEs are more likely to receive physical breast examinations and mammograms (ages > or =50). In addition, positive CoE findings for counseling on domestic violence, sexually transmitted diseases, family or relationship concerns, and sexual function or concerns were upheld. The CoE model of care delivers advantages to women that are not explained by the greater number of female physicians in these settings.