The aim of this study was to investigate the effects of smartphone use on the local dynamic stability while walking in young and healthy adults. To this end, 10 participants underwent repeated walking trials consisting of three conditions; 1) walking, 2) walking while texting, 3) walking while talking on a smartphone. In addition, to investigate the influence of walking speed, participants were instructed to undergo each condition at both a self-selected normal and self-selected fast walking speed. Data was gathered using a tri-axial accelerometer fixed at the lumbar level L4-L5. Local dynamic stability (LDS), defined by a maximum Lyapunov exponent (maxLyE), and gait variability, defined by standard deviation (SD) and coefficient of variation (CV) of stride time, and root mean square ratio (RMSratio), were assessed. The maxLyE increased significantly along the mediolateral axis, suggesting decreased stability in this direction when walking while texting compared to walking alone (p<0.05). Furthermore, the mean stride time decreased from self-selected normal speed to fast speed walking (p<0.05) and the variability in accelerations, as quantified by RMSratio along the mediolateral axis decreased significantly from walking while talking to walking alone (p<0.05). Similarly, significant decreases were observed for RMSratio of walking and texting at a fast speed to walking at a fast speed alone (p<0.05). These findings suggest that texting while walking decreases LDS and variability in the mediolateral direction in young, healthy, adults.