Dynamic fatigue behavior of high strength silica optical fiber was studied as a function of relative humidity of draw environment. Fibers were drawn with graphite induction heating furnace and controlled temperature, relative humidity and particle count of the draw environment i.e. drawing furnace to coating application point. Dynamic fatigue of the drawn fibers were measured with two different modes of loading, tensile & two-point bending. Draw humidity was found to have a decided impact on dynamic fatigue measured by tensile loading.