The purpose of the current study was to investigate the trunk angular kinematics (i.e., angle and angular velocity) during slip-induced falls and activities of daily living (ADLs), with the aim to facilitate the development of a new fall detector. Ten elderly participated in a laboratory experiment, composed of normal walking, slip-induced falls, and 5 types of ADLs. Sagittal trunk kinematics was measured from optical motion analysis system. Angular phase plots were utilized to characterize falls from ADLs.. Results indicated that backward falls were characterized by a simultaneous occurrence of a slight increase in trunk extension angle (average peak = 11°) and a dramatic increase in extension angular velocity (average peak = 139.7°/s). It was concluded that trunk angular kinematics could be used to design an effective fall detector.