Abstract: The Dynamic Bendloss Measuring Device allows easy, repeatable determination of the bend sensitivity of a single-mode optical fiber by subjecting the fiber to dynamically changing bend angles under varying degrees of tension and bend diameters. It utilizes a swing arm capable of sweeping an arc subtending a range of angles at any given bend diameter and fiber tension and calculating the bendloss from the light attenuation at each degree of the range. The varying bend diameters are provided by pins of diverse diameters that are singly inserted into an adjustably-sized aperture while the variation in the applied tension can be effected by changing the input current setting in the tension assembly. With each new pin and tension setting, the swing arm sweeps through the pre-selected range of bend angles, resulting in varying degrees of attenuation of light.