As activity levels of intensively managed broiler chicken vary over time, detailed knowledge on their influence is potentially useful to further adjust welfare assessment schemes. Therefore, this study investigated the influence of daytime and age on the performance of broiler chicken in two applied fear tests.On-farm studies were carried out in 14 flocks of intensively managed broiler chicken. A forced and a voluntary approach test were conducted during morning and evening hours and at three different ages (1: 6-12d; 2: 21-24d; 3: prior to slaughter). At each observation, avoidance distances (AD) and the number of animals voluntarily approaching (VA) an observer were collected.No significant correlation was found between daytime and AD or VA. When tested at different ages, daytime and VA were significantly correlated (1: r= 0.56*; 2: r= 0.40*; 3: r= 0.64*), but the results were not consistent. At three weeks the VA was found to be higher in the morning but at younger age and prior to slaughter, more birds approach an observer in the evening. Both, approach and avoidance peaked at three weeks and decreased prior to slaughter. Further, the effect of differing observer locations in the chicken house on the behavioural response of broiler chicken was studied. A higher proportion of birds voluntarily approached an unknown human in the area close to the main entrance door, but the avoidance behaviour was not affected.From the results of this study I conclude, that the time of assessment has no effect on avoidance or approach behaviour of commercial slow-growing broiler chicken. However, fear related behaviour changed depending on age. This makes the applied tests potentially applicable independent of daytime restrictions when performed with birds of the same age.