Ten cases of ertapenem neurotoxicity, mainly confusional states, are described, some of them with fatal outcomes. The majority of patients (90%) had a creatinine clearance (CrCl) < 50 mL/min/1.73m 2 at some point during treatment and hypoalbuminaemia was always present when ertapenem treatment was started. The pharmacokinetic and pharmacodynamic properties of this carbapenem could favour a different profile, and approved doses can be excessive in some patients with moderate renal failure (CrCl 31-59 mL/min/1.73 m 2). It may be necessary to re-evaluate renal function during treatment and adjust doses or reconsider the adequacy of treatment based on clinical judgement, especially if relevant changes in the CrCl occur (i.e. a reduction to ≤30 mL/min/1.73 m 2) or unexplained behavioural disorders are detected. The onset of the symptoms of ertapenem neurotoxicity can be insidious and go unnoticed, and so a knowledge and early suspicion of confusional states are important to improve the patient prognosis.