To investigate the relationship between methylation of syk (spleen tyrosine kinase) gene in promoter region and oncogenesis, metastasis in breast carcinoma.Using RT-PCR technique, specimens from 40 breast cancer patients (tumor tissues, adjacent normal tissues), 15 fibroadenoma were detected for their expression of the syk gene. Meanwhile, Methylation-specific PCR was used to detect methylation of syk promoter region.The expression of syk gene were detected in normal breast tissues and fibroadenoma samples, 9 out of 40 breast carcinoma samples were found the expression of syk mRNA, syk expression in breast carcinoma was lower than that in adjacent normal tissues and fibroadenoma samples. No methylation of syk promoter was found in adjacent normal tissues and fibroadenoma samples, 17 cases in 40 breast carcinoma patients (42.5%) were detected hypermethylation of syk gene in promoter region, the rate of methylation of syk promoter in breast carcinoma was higher than that of in adjacent normal tissues (P < 0.05). In 18 cases with lymph node metastasis, 14 were found with syk promoter methylation. A significant difference was noted between two groups (P < 0.05).Hypermethylation leads to lose of the syk gene expression in human breast carcinoma. Methylation of syk promoter may be correlated to oncogenesis, metastasis of breast carcinoma.