Study objective: We evaluate the effect of an Internet-based, electronic referral system (termed IMPACT-ED for Improving Medical home and Primary care Access to the Community clinics Through the ED) on access and follow-up at primary care community clinics for safety net emergency department (ED) patients.Methods: We conducted a nonblinded interventional trial at an urban, safety net, hospital ED with a census of 39,000 annually. IMPACT-ED identified patients who had no source of regular care and lived in a 15-ZIP-code low-income area served by 3 community clinics. Emergency physicians received an automated notification through the electronic medical record to access an imbedded software program for scheduling follow-up clinic appointments. Patients who would benefit from a follow-up clinic visit within 2 weeks as determined by the emergency physician received a computer-gene rated appointment time and clinic map with bus routes as part of their discharge instructions, and the clinics received an electronic notification of the appointment. We compared frequency of follow-up for a 6-month period before implementation when patients received written instructions to call the clinic on their own (pre-IMPACT) and 6 months after implementation (post-IMPACT). Statistical analysis was conducted with chi(2) testing, and corresponding 95% confidence intervals are presented.Results: There were 326 patients who received an appointment (post-IMPACT), of whom 81 followed up at the clinic as directed (24.8%), compared with 399 patients who received a referral (pre-IMPACT), of whom 4 followed up as directed (1.0%), for an absolute improvement of 23.8% (95% confidence interval 19.1% to 28.6%).Conclusion: Although most patients still failed to follow up at the community clinics as directed, the use of an Internet-based scheduling program linking a safety net ED with local community clinics significantly improved the frequency of follow-up for patients without primary care. [Ann Emerg Med. 2009;54:279-284.]