This invention relates to an industrially feasible process for producing HMG-CoA reductase inhibitor, simvastatin via novel intermediates, wherein the process comprises treating lovastatm or lovastatm ammonium salt with hydrazine or hydrazine derivatives to obtain lovastatin hydrazide intermediate, which is further used to produce simvastatin. Further, the hydroxyl groups of said intermediate are optionally protected to obtain protected lovastatin hydrazide intermediate and use the same to produce simvastatin.