Objective:To investigate the expression of sphingosine kinase 1 (SphK1) and its clinical significance in breast invasive ductal carcinoma ( BIDC).Methods: We detected SphK1 expression in 58 samples of surgically resected paired BIDC and normal tumor-adjacent tissues samples by using immunohistochemistry.The correlation between SphK 1 expression and clinicopathologic features was analyzed.Results: The positive expression rate of SphK 1 in BIDC tissues was 69.0% ( 40/58 ) , while its positive expression rate in normal tumor-adjacent was 17.2% (10/58),the difference was statistical significance (χ2=31.636,P=0.000). Clinicopathological evaluation suggested that SphK 1 positive expression was associated with ER negative (χ2=4.392,P=0.036),PR negative (χ2=7.920 , P=0.005 ) , lymph node metastasis (χ2 =5.033 , P=0.025 ) and tumor stage (χ2 =7.117 , P=0.008 ) . Conclusion:The high-expression of SphK1 is correlated with the poor clinicopathological features in BIDC ,suggesting SphK1 may play a key role in development and progression of BIDC.