BACKGROUND: Hypertonic solutions are considered to have a greater ability to expand blood volume and thus elevate blood pressure and can be administered as a small volume infusion over a short time period. On the other hand, the use of hypertonic solutions for volume replacement may also have important disadvantages. OBJECTIVES: To determine whether hypertonic crystalloid decreases mortality in patients with hypovolaemia with and without head injuries. SEARCH STRATEGY: We searched MEDLINE, EMBASE, The Cochrane Controlled Trials Register and the Specialised register of the Injuries Group. We checked reference lists of all articles identified and searched the National Research Register. SELECTION CRITERIA: Randomised trials comparing hypertonic to isotonic crystalloid in patients with trauma, burns or undergoing surgery. DATA COLLECTION AND ANALYSIS: Two authors independently extracted the data and assessed the quality of the trials. MAIN RESULTS: Seventeen trials were identified with a total of 869 participants. Data on death were obtained in twelve of the studies. Only one trial reported data on disability. The pooled RR for death in trauma patients was 0.84 (95% CI 0.61-1.16), in patients with burns 1.49 (95% CI 0.56-3.95), and in patients undergoing surgery 0.62 (95% cI 0.08-4.57). In the one trial that gave data on disability using the Glasgow Outcome Scale the relative risk was 0.99 (95% CI 0.06-15.93). REVIEWER'S CONCLUSIONS: This review does not give us enough data to be able to say whether hypertonic crystalloid is better than isotonic crystalloid for the resuscitation of patients with trauma, burns, or those undergoing surgery. However, the confidence intervals are wide and do not exclude clinically significant differences. Further trials are needed comparing hypertonic to isotonic crystalloid. Trials need to be large enough to detect a clinically important difference.