This paper describes a previously sufficiently functioning 57 year old man who presented with a recent onset of frontal behaviour. Partial agenesis of corpus callosum was an incidental finding on a computerized tomography scan. The EEG was within normal limits and neuropsychological testing did not reveal any interhemispheric disconnection. A SPECT-Scan revealed bilateral hypoperfusion, consistent with Alzheimer's dementia. Normal functioning up to 50 years of age and a later manifestation of Alzheimer's disease along with agenesis of carpus callosum is of clinical interest as such an association has not been published.