Two cases of neuroleptic malignant syndrome are reported. Although affecting chiefly psychiatric patients, this rare, polymorphic disease should be well-known to internists, general practitioners, and emergency staff because of its high risk of fatality. Our patients, who presented without some of the main symptoms, fell in the category of incomplete variants of the syndrome, the most difficult to recognize. In both patients, computerized tomography carried out at the outset of symptoms, evidenced signs of cerebral edema, a datum never before reported. The symptomatic polymorphism, pathogenesis, differential diagnosis, and therapy of this disease are illustrated and discussed.