The detection of vulnerable road users (VRUs), especially under time constraints, may be impaired in elderly drivers, due to their visual and cognitive decline. This represents a major concern for road safety. The objective of the present study was to investigate the effect of aging on the detection of VRUs. A further aim was to investigate the impact of external factors on VRU detection. Twenty-two young adults, 20 younger-old adults, and 32 older-old adults were included in the study. A series of photographs were displayed for 500 ms. Participants were asked to detect the VRU, which could be a motorcyclist, a cyclist, or a pedestrian. The VRU was located at one of two distances (near/far), one of two locations (off-centered/centered), and in two car-DRL (daytime running lights) environments (on/off). The ability to correctly detect a VRU was measured. An eye-tracker was used to record eye movements. The main findings showed that VRU-detection performance decreased with aging, even in the younger-old group (ages 55-68). The ability to correctly detect a VRU by older-old adults was poorer particularly when the VRU was a motorcyclist or a cyclist. As a whole, the older-old adults made more fixations to correctly detect the VRU than the other two age groups did. Moreover, the visual angle between the gaze of the participant's last fixation and the target in the older-old group was lower than in the other two groups, particularly when the VRU was off-centered. This finding suggests that older-old adults compensated for their visual-field decline by doing more visual exploration than the other two groups did to correctly detect the VRU. The results are discussed with regards to age-related cognitive and visual deficits.