The aim of this study was to assess whether proprioceptive information of trunk muscles as a reference frame plays a role in determining directions. Eleven young healthy right-handed male subjects (age: 23.78 ? 0.78 years, height: 169.7?5.7 cm, and mass: 62.8 ? 6.8 kg, BMI: 22.34? 1.7 kg/m2) volunteered to participate in this study. Unilateral trunk muscle vibration was applied either from the beginning or the middle of a seven-step task with their eyes open (OE) or blindfolded. The deviation from the walking path was determined as the distance of the seventh footprint from the first one along the mediolateral axis. Foot angles and stride lengths were calculated for all footprints. All deviations from the straight path were measured by footprint deviation from the reference line on the ground. Two-way repeated measure ANOVA (two vision conditions and three vibration conditions) was used to test the significant difference in distance parameter. Three-way repeated measure ANOVA (vision and vibration conditions and angle of footprint) was used to determine the difference between the mean angle of foot deviation from the reference line and stride length within and in the middle of the three vibration conditions and two vision conditions. The results showed that vibration produced a clear-cut deviation from the straight direction when delivered in the middle of blindfolded locomotion (P=0.0.1). The deviation was much smaller with OE (P=0.06). A mild deviation was obtained in blindfolded condition when vibration started at the beginning of locomotion (P=0.77). Trunk proprioception plays a major role in defining locomotor trajectory.