BRCA1　promoter　methylation　is　an　essential　epigenetic　transcriptional　silencing　mechanism,　related　to　breast　cancer　(BC)　occurrence　and　progression.　We　quantified　the　methylation　level　of　BRCA1　promoter　and　evaluated　its　significance　as　prognostic　and　predictive　factor.　BRCA1　promoter　methylation　level　was　quantified　by　pyrosequencing　in　surgical　cancerous　and　adjacent　normal　specimens　from　154　BC　patients.　A　follow　up　of　98　months　was　conducted　to　assess　the　correlation　between　BRCA1-methylation　level　vs.　overall　survival　(OS)　and　disease　free　survival　(DFS).　The　mean　methylation　level　in　BC　tissues　was　significantly　higher　(mean　32.6%;　median　31.9%)　than　in　adjacent　normal　samples　(mean　16.2%;　median　13.0%)　(P　＜　0.0001).　Tumor　stage　(R　=　0.6165,　P　＜　0.0001)　and　size　(R　=　0.7328,　P　＜　0.0001)　were　significantly　correlated　with　the　methylation　level.　Patients　with　unmethylated　BRCA1　had　a　better　OS　and　DFS　compared　to　the　methylated　group　(each　P　＜　0.0001).　BRCA1　promoter　methylation　level　has　a　statistically　significance　on　survival　in　BC　patients　(HazR　=　1.465,　P　=　0.000)　and　is　an　independent　prognostic　factor　for　OS　in　BC　patients　(HazR　=　2.042,　P　=　0.000).　Patients　with　ductal　type,　HER2　negative,　lymph　node　negative　stage　1　+　2　tumors　had　a　better　OS　and　DFS.　Classification　of　grades　and　molecular　subtypes　did　not　show　any　prognostic　significance.　Pyrosequencing　is　a　precise　and　efficient　method　to　quantify　BRCA1　promoter　methylation　level,　with　a　high　potential　for　future　clinical　implication,　as　it　identifies　subgroups　of　patients　with　poorer　prognosis.