A best evidence topic was constructed according to a structured protocol. The question addressed was 'Does perioperative furosemide usage reduce the need for renal replacement therapy in cardiac surgery patients?' Forty-seven papers were found using the reported search, of which 10 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Current best available evidence to resolve the issue includes a systematic review and nine randomized controlled trials (RCTs). The systematic review of seven RCTs and one observational study has demonstrated that in patients who have undergone cardiac surgery, a more consistent and sustained diuresis is produced by a continuous infusion of furosemide compared with intermittent bolus doses of furosemide. However, there does not appear to be a significant difference in the total urine output or a change in serum electrolyte levels when furosemide is administered as a continuous infusion compared with intermittent bolus doses. Three RCTs recruiting neonatal and paediatric patients after open heart surgery also validated the safety and efficacy of furosemide infusion as well as intermittent bolus doses. Two of the five RCTS in adult cardiac surgery patients showed that furosemide infusion was associated with a reduced need for renal replacement therapy (RRT), while two RCTs failed to show any benefit and one reported an increased incidence of renal impairment. We conclude that continuous furosemide infusion in the perioperative period promotes a gentle and sustained diuresis in cardiac surgery patients. The evidence supporting the benefit of this strategy in terms of reducing the need for RRT is weak. At the same time, current best available evidence, albeit from small RCTs, suggests that the timely introduction of continuous furosemide infusion does not increase the incidence of renal impairment after cardiac surgery.