A survey was distributed, using a sequential mixed-mode approach, to a national sample of obstetrician–gynecologists. Differences between responses to the web-based mode and the on-paper mode were compared to determine if there were systematic differences between respondents. Only two differences in respondents between the two modes were identified. University-based physicians were more likely to complete the web-based mode than private practice physicians. Mail respondents reported a greater volume of endometrial ablations compared to online respondents. The web-based mode had better data quality than the paper-based mailed mode in terms of less missing and inappropriate responses. Together, these findings suggest that, although a few differences were identified, the web-based survey mode attained adequate representativeness and improved data quality. Given the metrics examined for this study, exclusive use of web-based data collection may be appropriate for physician surveys with a minimal reduction in sample coverage and without a reduction in data quality.