This report examines the relation of upper and lower extremity motor performance to functional impairment among 371 persons with probable Alzheimer's disease (AD). Cognitive and motor performance tests were administered at 6-month intervals for up to 4 years. Motor performance was assessed using 3 lower extremity tests and 2 upper extremity tests. Functional impairment was measured at 3-month intervals using caregiver ratings of impairments in activities of daily living, mobility, and range of motion. Both lower and upper extremity performance were inversely related to functional impairments on all 3 scales (all Ps < .001), after controlling for age, sex, and level of cognitive impairment. This suggests that motor performance contributes to functional impairments in AD, independent of cognitive impairment. It is important to preserve motor performance in individuals with AD because it influences physical function throughout the course of the disease.