Abstract: Objective　 To investigate the serum level of tissue factor (TF) and mRNA expression in monocyte from patients with gastrointestinal tumor. Methods The TF level was determined in 32 gastric cancers, 45 colorectal carcinomas, 30 normal persons were determinated with ELISA, RT-PCR was used to detect expression of mRNA in monocyte. Results The high serum TF level was found in gastrointestinal tumor. TF mRNA in monocyte can be detected in most of cancer patients whereas it is undetectable in normals. Conclusions Expression of TF mRNA in monocyte probably accounts for high level of TF level in serum, TF value and mRNA expression can be a useful tool for early diagnosis and studying pathological processes.