Neuroleptic malignant syndrome is a serious adverse reaction of neuroleptic drug therapy, composed of mental status changes, muscular rigidity, hyperthermia, signs of autonomic instability and typical laboratory findings. The syndrome has received increased attention in the scientific literature since 1980; nevertheless some weighty issues regarding clinical symptoms, etiopathogenesis and treatment require additional studies. This paper presents 9 cases of neuroleptic malignant syndrome prospectively observed in 8 inpatients and 1 outpatient with different psychiatric diagnosis. Levenson's diagnostic criteria were fulfilled in 7 cases; the remaining two had slighter symptoms. So neuroleptic malignant syndrome is to be considered a rare but not unusual side effect of neuroleptics. The risk of syndrome doesn't seem to be correlated with chemical class, D2 receptor affinity and total dosage of neuroleptics; a key factor seems instead to be a quick loading rate of neuroleptics. Seven of 9 cases displayed severe changes in mental status (clouding of consciousness that varies from stupor to coma), violent psychomotor excitement and aggressiveness before the onset of the syndrome. Such clinical features seem themselves, in our experience, to be potential risk factors besides reason for an increase of neuroleptic dosage. Neuroleptic malignant syndrome usually is preceded by prodromal signs, the most important appearing the worsening of alterations in consciousness. Symptoms of neuroleptic malignant syndrome usually appear abruptly and in some cases with a dramatic course; they last, in cases with favourable outcome, a few days to two weeks from neuroleptic withdrawal; by far the worst outcome, instead, occurs if diagnosis and drug discontinuation are not carried out early. The first measure in the treatment of neuroleptic malignant syndrome consists of prompt discontinuation of all neuroleptic medications and other psychopharmacological cures, except for benzodiazepines, and institution of supportive therapy; such interventions can resolve the most of cases. Three patients treated with bromocriptine and/or dantrolene didn't display a different duration of clinical symptoms and rate of complications if compared to patients treated with supportive therapy only. Use of bromocriptine or dantrolene, or both, therefore should be considered as a second line of action. In four cases, neuroleptics were reintroduced within few days of recovery; low potency neuroleptics were employed, given low doses which gradually increased: in none of the 4 cases did the patients experience partial or complete recurrence of neuroleptic malignant syndrome.