An optical fiber cable which has metallic components,either in the sheath or in the core,is susceptible to lightningdamage.The reasons for having metallic components may be to provide tensile strength,moisture barriers, rodentprotection andor communication (“talk-pair”) facilities. Cable locating for maintenance and repair activities is alsofacilitatedby metal in the cable.The fact that lightningcan damage fibers in such cables has been evidenced in the fieldand in lightning simulationexperiments [I].This methodology provides two numerical approaches to estimating the primary damage rate.Primary damage refers to instances where the fiber is out of service.The result yielded by the first assessment technique is useful for comparison purposes whether various route designsor cable designs are being evaluated. It may also be used when an absolute value is needed.The result yielded by the second assessment technique may be used when a conservative value for Annual Damage Rate is needed, or for comparative studies.Work is currently under way to study the actual field damage rates and compare them to the calculatedrates.Secondary damage, for instance pinholing which may increase the corrosion rate,can be evaluated by means of the formulas given in Appendix 5 of Chapter 7,or by the algorithmspresented in [5].Any lightning damage mitigation technique,e.g. route redundancy, shield wires,more rugged cable, etc.should only be considered in cases where the lightning damage rate is significant in comparison to other sources of cable damage,e.g. cable cuts.Improvement in the overall system availabilitycan be calculatedusing the methods given.