The basis of hypersexual behavior among patients with dementia is not entirely clear. Hypersexual behavior may be a particular feature of behavioral variant frontotemporal dementia (bvFTD), which affects ventromedial frontal and adjacent anterior temporal regions specialized in interpersonal behavior. Recent efforts to define hypersexual disorder indicate an increasing awareness of heightened sexual activity as a source of personal distress and functional impairment, and clarification of hypersexuality in bvFTD could contribute to understanding the neurobiology of this behavior. This study reviewed 47 patients with bvFTD compared to 58 patients with Alzheimer's disease (AD) for the presence of heightened sexual activity to the point of distress to caregivers and others. Hypersexual behavior occurred in 6 (13 %) bvFTD patients compared to none of the AD patients. Caregivers judged all six bvFTD patients with hypersexual behavior as having a dramatic increase in sexual frequency from premorbid levels. All had general disinhibition, poor impulse control, and actively sought sexual stimulation. They had widened sexual interests and experienced sexual arousal from previously unexciting stimuli. One patient, with early and predominant right anterior temporal involvement, was easily aroused by slight stimuli, such as touching her palms. Although previously considered to be predominantly disinhibited sexual behavior as part of generalized disinhibition, these patients with dementia illustrate varying degrees of increased sexual desire. We conclude that bvFTD is uniquely associated with hypersexuality; it is more than just cognitive impairment with frontal disinhibition but also involves alterations in sexual drive, possibly from right anterior temporal- limbic involvement in this disease.