OBJECTIVE: To report on the response rate achieved in a survey of medical practitioners and discuss the reasons for it. METHOD: An on-line (internet-based) survey of all 609 registered pharmacotherapy prescribers in Victoria and Queensland; invitations to participate were sent by mail in late April 2007, and one reminder letter in late May 2007. RESULTS: Six hundred and nine invitation letters were mailed, nine were returned to sender, and 52 questionnaires completed, making the overall response rate 52/600 = 8.7%. The response rate in Queensland was 13.2% (16/121), and in Victoria 7.5% (36/479). CONCLUSIONS: Despite utilising sound techniques, our response rate was much lower than those achieved in recent Australian paper-based surveys of medical practitioners. It is possible that the issue being addressed (injecting-related injuries and diseases) was not of high priority for many invitees, leading to reduced response. IMPLICATIONS: On-line surveys are not yet an effective method of collecting data from Australian medical practitioners; researchers should continue to use paper questionnaires for maximum response.