Primary polydipsia (PP) is a frequent complication that affects many chronic schizophrenic inpatients. Due to possible lethal consequences, for example, hyponatremia, coma and death, it's fundamental for the physician achieving early diagnosis and treating this condition. The first step is identifying polydipsia by clinical, biochemical and pharmacological means. Nowadays, the pathophysiology of PP remains unclear, and this limits the possibility of detecting an appropriate drug treatment. Typical antipsychotics have been associated to a worsening of polydipsic behavior, while more recently atypical antipsychotics have been reported as being useful. However results are still mixed and controversial. It appears that risperidone and olanzapine are not clearly effective; clozapine may improve symptoms, although it is difficult to manage from a therapeutic point of view; quetiapine has been poorly studied so far, nonetheless it has given interesting results. Through a case study analysis, this report presents a brief, yet selective, overview of the current state of psychopharmacology in the treatment of PP with atypical antipsychotics in schizophrenia.