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/1.73m2 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 m2). 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 m2) 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.