Availability and other related parameters, such as failure frequency, mean down Lima, otc, aro important reliability parameters to be considered at the design stage of a system; and this needs appropriate mathematical models for their assessment. This paper presents algorithms to assess quantitatively the above parameters of a repairable m-ordor system comprising units with unequal failuro and repair rates. The concepts of minimal cut sets and minimal tie sets have been employed. The modols developed here can be applied to series and parallol systems as well.