Spatial and temporal gait parameters in 40 patients with early Alzheimer's disease (AD) were compared to that of 34 normal controls (NC) on a level ground and on a treadmill. Over-ground velocity, cycle-time, cadence, stride-length, stride-width and double-support time were captured on an electronic walkway. On the treadmill, cadence, cycle-time and double-support time were recorded at a preferred velocity using footswitches. The AD group were significantly slower on the Timed Up and Go task compared to NC (p<0.05). AD patients differed significantly from the NC on their over-ground gait velocity (99+/-19 cm/s vs 119+15 cm/s, p<0.001), cadence (101+/-9 steps/min vs 109+/-9 steps/min, p=0.001) and stride-length (118+/-18 cm vs 131+/-17 cm, p<0.01). On the treadmill, only preferred speed was significantly different in the AD group compared to the NC group (60+/-20 cm/s vs 74+/-23 cm/s, p=0.02). These results indicate that patients with early AD walk slower and with shorter strides than healthy older adults.