Dear Priya, you haven't mentioned the entrance examination that you are enquiring about. However, GATE has a validity of 3 years. With an ecxeption to GATE, almost all entrance examinations which are being conducted for admission into specific course, are valid only for that particular year. MAT is valid for 1 year from the time the results have been declared. XAT is valid until December 31st of the year that you have given the exam in. CAT is also valid for 1 year. If you have any entrance exam in mind, please do let us know.