Lithium is one of the drugs used widely in the treatment of mood disorders. However, it has a very narrow therapeutic index and side effects can be seen in many organ systems, one of which affects the kidneys. We can see varying degrees of renal damage associated with acute or chronic lithium use. Lithium intoxication is diagnosed by a rise in the serum lithium concentration, but it must be remembered that serum levels and clinical findings do not always overlap. Treatment of lithium intoxication varies according to the clinical findings. There are various ways of treating lithium intoxication, but there is no specific antidote. The purpose of treatment is to remove the toxin from the body. Here we report a patient who was treated for lithium intoxication and developed diabetes insipidus during follow-up, and discuss the relevant literature.