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The purpose of this study was to explore the modifications in saggital and frontal dynamic stability during stair descent while texting to provide a database for guidelines of fall prevention. Participants (n=26; 13 male, 13 female) performed three stair descent trials under texting and No texting task conditions at self-selected speed, respectively. Synchronous kinematics and kinetics were collected by an eight-camera Vicon infrared motion capture system and two force platforms. A paired sample t-test was used to analyze the differences between two task conditions. With the interference of texting, anterior–posterior margin of stability (MOSap) increased in the initiation of double-support phase (DSP), while decreased in the initiation of single-support phase (SSP), medial–lateral MOS (MOSml) decreased in the initiation of SSP. Posterior instability was induced in the initiation of DSP. The initiation of DSP was the most unstable moment and should alert texters, particularly young adults, to potential risk of falling backward during stair descent.