The paper describes a patient with Asperger disorder, Neurogenic Diabetes Insipidus (NDI) and Primary Empty Sella (ES). His response to vasopressin treatment suggested a concomitant presence of primary polydipsia. This is the first reported case of an autistic spectrum disorder associated with NDI or ES. The implications of the observed co-occurrence of these relatively rare disorders are discussed in relation to diagnosis and pathogenesis.