The author has proposed a new modified Weibull distribution function for the analysis of strength data of optical glass fibers. The main purpose of this letter is to analyze the fatigue failure of optical fibers in terms of this equation along with fracture mechanics theory. There is good agreement between the predicted and measured distributions indicating that fatigue failure of polymer-coated optical glass fibers occurs by slow growth of pre-existing flaws and that fracture mechanics theory together with the proposed distribution function can be used in making fatigue-failure predictions of these materials.