The National Acute Brain Injury Study: Hypothermia (NABIS:H) is an ongoing multicenter trial of systemic hypothermia for the treatment of severe head injury. Follow-up rates for the study's 3-and 6-month outcome assessments have been maintained at high levels by establishing close contact with family members, by reimbursing cost of travel, and by sending examiners to the subject's location whenever necessary. Two years into the study, global disability data (e.g., Glasgow Outcome Scale) have been obtained on 86% of patients due for 3-month assessment (n = 131) and for all subjects due at 6 months (n = 100). Over half of the patients have completed neuropsychological testing with high reliability ratings. These preliminary findings suggest that the procedures used to document data quality and increase follow-up and completion rates are being successful.