Early mobilization following hip fracture surgery reduces medical complications and mortality, but may increase the risk of falling. The aim was to measure objectively the physical activity (time spent upright) the first week after hip fracture surgery, and relate it to functional performance and fear of falling at discharge. The 24-hour upright time was measured for a median of 6 days using a thigh-worn accelerometer in 37 patients (mean 80 years ± 8.4) and increased from median 13 (IQR 6-31) minutes to 46 (11-107) minutes at day 7. More upright time at discharge was associated with less fear of falling (r=-0.48, p=0.01, n=27), which also was associated with fast gait speed (r=-0.50, p=0.02, n=23) and a faster Timed Up and Go test time (r=0.54, p < 0.01, n=22), indicating a need for further studies on motivation and limitations for more physical activity following hip fracture surgery.