Objective: Achieving high survey participation rates among physicians is challenging. We aimed to assess the effectiveness of response-aiding strategies in a postal survey of 1,000 randomly selected Australian family physicians (FPs). Study Design and Setting: A two × two randomized controlled trial was undertaken to assess the effectiveness of a mailed vs. faxed prenotification letter and a mailed questionnaire sealed with a label marked attention to doctor vs. a control label. At the time of our final reminder, we randomized remaining nonresponders to receive a more or less personalized mail-out. Results: Response did not significantly differ among eligible FPs receiving a prenotification letter via mail or fax. However, 25.6% of eligible FPs whose questionnaires were sealed with a label marked attention to the doctor responded before reminders were administered and compared with 18.6% of FPs whose questionnaires were sealed with a control label (P = 0.008). Differences were not statistically significant thereafter. There was no significant difference in response between FPs who received a more vs. less personalized approach at the time of the final reminder (P = 0.16). Conclusion: Mail marked attention to doctor may usefully increase early response. Prenotification letters delivered via fax are equally effective to those administered by mail and may be cheaper.