Abstract: Catatonia is a relatively common condition with an estimated prevalence of 0.6% to 17% among youth with psychiatric disorders. Certain patient groups, such as those with autism, may be at a particularly high risk for catatonia. Most of the youth with catatonia are males with a diagnosis of a bipolar disorder. We describe here 2 adolescent females, both with Down syndrome, who presented with catatonia not accompanied by significant affective or psychotic symptoms or with a general medical condition. Both patients had functioned well until the onset of catatonic symptoms. In the current classification system used in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, catatonia is described in association with schizophrenia, as a specifier of affective disorders or secondary to general medical conditions. The cases described here highlight the problem with this classification system when patients fail to meet any of the 3 diagnostic categories under which catatonia is currently described.