Objective To delineate the differences in nocturnal wandering behavior between patients with Alzheimer's disease (AD) and with frontotemporal dementia (FTD).Methods The study was conducted in a dementia care unit at a hospital in Osaka,Japan from September 2008 to September 2009.Twenty-four-hour movements of 27 ambulatory inpatients with AD and 7 inpatients with FTD were recorded consecutively by the IC tag monitoring system.Results There were no significant differences in the distribution of sex,duration of dementia,clinical dementia rating (CDR) and mini-mental state examination (MMSE) scores between two dementia types.However,patients with FTD were much younger than those with AD [(63.43± 14.93) yr vs.(73.89 ±9.12) yr,t=5.56,P＜0.05],and age of onset were significantly different between two dementia types [(58.17±15.16) yr vs.(70.16±9.26) yr,t=6.30,P＜0.05].There was increased distances moved during 6∶ 00-23 ∶ 59 in FTD group comparing with AD group [(4842.44 ± 2617.94)m vs.(2119.39 ±2535.59)m,Z=2.66,P＜0.01],while difference in distances moved during 0 ∶ 00-5 ∶ 59,frequency and intensity of nocturnal ambulation were not significant(P＞0.05)between two groups.Further study showed that AD wanderers had longer distance moved during 0 ∶ 00-5 ∶ 59 [(85.17±142.42)m vs.(1.19±1.71)m] with shorter distance moved during 6 ∶ 00-23 ∶ 59 [(2119.39±2535.59)m vs.(4151.96±1881.35)m],and increased frequency [(0.64±0.29) vs.(0.33±0.22)] and intensity of nocturnal ambulation [(0.21±0.13) vs.(0.07±0.05)],compared with those with frontal variant FTD (all P＜0.05).Conclusions AD patients have more severe nocturnal ambulation than those with frontal variant FTD,which suggests that the increased monitoring and clinical interventions during nighttime should be taken for AD wanderers.