OBJECTIVE: The study aimed at assessing the impact of the introduction of a bicarbonated saline solution on total fluid load, weight gain and acid base status during acute burn resuscitation. DESIGN: Based on a retrospective patient record review. SETTING: Burn care centre of a surgical ICU in a tertiary university hospital. PATIENTS: Two groups of adult patients (20/20), with thermal burns of 25% or more body surface area were studied. INTERVENTION: Modification of the resuscitation fluid composition from lactated Ringer's solution (LR: Na 132 mmol/l, Cl 112 mmol/l, 263 mosm/l), to bicarbonated 0.9% saline (BS: Na 180 mmol/l, Cl 154 mmol/l, 340 mosm/l) METHODS: Age, weight, burn size and depth, inhalation injury, fluid intakes over 48 h post-injury, plasma sodium, chloride, creatinine, albumin levels, blood gases and ventilation support were recorded. RESULTS: The demographic characteristics of the patients (41 +/- 16 years) in the two groups were not different, with severe burns involving 44 +/- 17% body surface area. While the total fluid volumes administered did not differ, BS was associated with lower plasma pH, base excess and bicarbonate levels for 24 h and with hyperchloraemia. Clinical evolution did not differ. CONCLUSIONS: Using bicarbonated saline solution for resuscitation causes a transient hyperchloraemic dilutional acidosis compared with LR, and has no other detectable clinical impact over the first 10 days after severe burn injury.