Anxiety in sport horses affects their performance, health, and value, as well as the reputation of trainers and competitors. The objective of this study was to determine whether laser acupuncture (LAP), when given before stressful situations, can decrease anxiety and improve performance and health in horses. A 2×2 crossover study was conducted on 24 horses randomly assigned to one of the two groups: Group A – given LAP on Day 1; Group B – given sham LAP with the laser powered off on Day 1. The treatments were switched between the two groups after a 7-day wash-out period. All horses were fitted with a heart rate (HR) monitor before undergoing an acute startle test (AST). Each subject’s HR was recorded continuously from 1 minute before to 10 minutes post the AST. The primary outcome data for assessing the treatment effect were HR increase from the baseline (peak HR – baseline HR) following the AST and the time duration needed for HR to return to baseline level (time between peak HR and baseline). The observed outcome data concluded: (1) horses treated with LAP had a smaller HR increase than those treated with sham LAP (p=0.036), and (2) the time it took for the resulting peak HR to return to baseline was shorter in horses treated with LAP than those treated with sham LAP (p=0.045). These findings indicate that laser acupuncture before a known stressful situation could help a horse accept the stressful situation and recover back to homeostasis more rapidly.