This document outlines a methodology for generating and allocating diagnostic requirements for avionics and electronic systems and equipment. The diagnostic requirements to be generated include Fault Detection, Fault Isolation and False Alarm rates. These parameters, along with Time to Detect and Time to Isolate are then allocated to the equipment or replaceable item (RI) level. To achieve the allocations for detection and isolation times, it is also necessary to allocate a top Maintainability (MTTR) Requirement.The diagnostic requirement methodology described herein is built around its relationship to maintainability, MTTR in particular. The approach was formulated in this way because diagnostic parameters are a subset of reliability and maintainability, and a strong mathematical foundation is available within R&M to build a mathematical approach to diagnostic requirements allocation.