Abstract: In this paper, we analyse two-unit cold standby system with instructions and post-repair inspection. On the failure of a unit, an expert repairman comes with his assistant and gives instructions to his assistant for repairing the unit. After getting instructions, the assistant repairman immediately starts the repair of the failed unit. When the assistant completes the repair, the inspection is carried out by the expert to see whether the unit repaired by his assistant is perfectly repaired or not. If not, the expert himself repairs it perfectly. Various measures of the system effectiveness are obtained by making use of semi-Markov processes and regenerative point technique. Study through graphs is also made.