Introduction. Exception from informed consent trials require subsequent notification of enrollment to patients’ legally authorized representatives. Objective. To describe the subsequent notification process utilized by one site during a prospective, randomized, controlled prehospital clinical trial. Methods. The institutional review board–approved subsequent notification process was implemented for all patients pronounced dead in the field or in the emergency department. Demographic information, including incident address and patient address, was collected by the study coordinator. A mailing was sent via standard U.S. mail to the last known accurate patient address within two weeks of accessing that information. The mailing included an informational letter notifying the recipient of the patient’s enrollment in the trial and requested return of a response card to assess the respondent’s prior knowledge of this study and his or her desire for a phone call follow-up with the principal investigator. The number of mailings per patient, outcome of the mailing, number of recipients requesting a phone call follow-up, and number of recipients with previous knowledge of the study were calculated. Results. Between March 2006 and July 2009, a total of 376 patients were formally enrolled into the study, with 255 (68%) requiring subsequent notification. 42% of enrolled patients had one mailing sent to the last known address, with study staff sending two mailings to the remaining patients. Initial mailings were returned undeliverable in 32% of patients (81/253). The certified letter receipt of delivery was the only subsequent notification contact in 76 of 253 patients (30%). 33% of mailing recipients (83/253) returned the response card to the investigators. Of the 83 individuals who returned the response card, 34% requested a phone call from the principal investigator. Only four people (4.8%) who responded to the subsequent notification mailing stated they had heard of this study prior to receiving the subsequent notification information. Conclusion. The return rate of response cards and requests for follow-up phone calls were higher than anticipated. In the future, use of certified mailings for the initial mailing is warranted. The high level of nondeliverable mailings is concerning, but must be balanced with the time and expense of identifying additional and accurate contact information.