Objective: Improve documentation during a mass casualty incident (MCI).Design: This is a retrospective chart review.Setting: This chart review was done in the Major Incident Hospital (MIH). The MIH is a highly prepared back-up hospital in the center of the Netherland that can be deployed in case of a major incident.Patients, participants: Until recently, the MIH used an extensive paper medical record: the hospital in special circumstances medical record (HSCMR). A concise primary survey form was developed and attached to the HSCMR, forming the pilot disaster medical record (pDMR). In this retrospective chart review, primary survey data documented in the HSCMR (during a MCI) were compared to the pDMR (during a drill exercise). Three triage categories were used: T1, immediate; T2, urgent; and T3, delayed.Main outcome: The MIH hypothesized that a dedicated, concise, and practical primary survey form could improve quantitative patient documentation during an MCI. Significant differences were tested with the chi square and Fisher exact test (p 0.05).Results: The pDMR was used significantly more often 61 percent vs 89 percent (p = 0.001), especially in T1 and T2 patients. Quantitative documentation in the pDMR improved significantly on airway, breathing, breathing frequency, saturation, circulation, heart rate, blood pressure, Glasgow Coma Score, exposure, and medication given but not in cervical spine and temperature. Conclusion: Significantly more primary survey forms were used and more data were documented using the pDMR, especially in the most critical patients. An MCI medical record should be simple and concise and should not deviate from daily routine.