BackgroundGait mechanics alternation is one of side effects after anterior cruciate ligament reconstruction (ACLR). Foot roll-off characteristics shows whole gait mechanics and is not well known in ACLR patients. The purpose of present study was to investigate the roll-off process characteristics while walking and running in patients with ACLR history. Research questionIs there any difference in walking and running roll-off characteristics between patients with ACLR history and healthy individuals? Methods48 physically active males (24 healthy and 24 with ACLR history) participated in this study. Participants walked and ran on a footscan (Rsscan International) which was mounted in the midway of a 18 m runway at the speeds of 2 m·s−1 and 3.3 m·s−1. Center of pressure (COP) trajectory, timing of stance subphases, foot progression angle and contact time were calculated bilaterally in walking and running. Mixed-design MANOVA was used to examine effect of ACLR on the outcomes. ResultsThe results showed that ACLR participants had greater foot progression angle (p = .001) and more medially oriented COP trajectory in forefoot push-off phase (FFPOP) of waking (p = .001) and running (p = .001), but showed shorter contact time in running compared to healthy group (p = .02). Involved leg in ACLR group showed greater foot progression angle (p = .001) and more medially directed COP trajectory in FFPOP of walking (p = .001) and running (p = .01) compared to uninvolved side. Also, involved leg had shorter contact time (p = .04) and shorter relative time in the forefoot contact phase (p = .001), and longer relative time in forefoot flat phase (p = .001) during running. SignificanceBased on the results, it can be concluded that ACLR affects running and walking roll-off characteristics which can show altered mechanics. Running shows remarkable differences in roll-off process than walking. So, it is recommended to use running in post-ACLR assessments rather than walking.