New approaches to improve the prediction of failure of long length fibers are presented. They are currently being used in type approval and quality control of optical fibers and cables in Swedish Telecom. One approach is to use the B-parameter. Values on this parameter, usually obtained from testing in liquid nitrogen, high temperature, or under vacuum, are not being considered very useful for lifetime estimation in regular environments. Therefore, a high- speed tensile test has been developed, by which the B-parameter is evaluated, at adequate service conditions. The other approach, to long-term fatigue data, is the expander test by which static and dynamic tests are made on medium length fibers under uniaxial stress. Long- term failure statistics are conveniently accessed by testing a single specimen. Limitations of the techniques are discussed: influence on fatigue parameters of static versus dynamic load and testing environment, and fatigue of high strength versus low strength modes.