Lithium is, in the era of evidence-based psychiatry, an efficacious and, simultaneously, cost-effective treatment for bipolar disorder, despite the existence of alternative mood-stabilizers (antiepileptics, atypical antipsychotics). A prerequisite for lithium administration in patients with bipolar disorder is the patient 's cooperation, in order to ensure monitoring of drug plasma levels as well as thyroid and renal function. Lithium-related renal complications include impairment in renal concentrating ability resulting in polyuria, increase of plasma creatinine levels and, more rarely, renal insufficiency. In this paper we present the case of a patient with bipolar disorder, who developed chronic renal insufficiency after 25 years of treatment with lithium.