Objective To investigate the expression of Notchl and NUMB in gastric cancer and explore the relationship between two genes and clinicopathologic features. Methods The mRNA and protein expressions of Notchl and NUMB in the gastric cancer tissues and normal gastric tissues were determined by realtime PCR and Western blotting. Results The mRNA expression of Notchl in gastric cancer tissues was 1.67times that of Notchl in normal gastric tissues. The increase of the mRNA expression of Notchl was correlated with tumor differentiation and lymph node metastatis of the patients ( P < 0. 05 ). The mRNA expression of NUMB in gastric cancer tissues was 0.597 times that of Notchl in normal tissues. The decrease of the mRNA expression of NUMB was correlated with tumor differentiation of the patients (P < 0.05). The expression of Notchl was negatively correlated to that of NUMB ( r = - 0.459, P < 0.05 ). The protein expression of Notchl in gastric cancer tissues was (0. 348 ±0. 133) , which was significantly higher than (0. 208 ±0. 140) in normal gastric tissues (P < 0.05 ). The protein expression of NUMB in gastric cancer tissues was (0.490 ±0.440), which was significantly lower than 0.746 ±0.390 in normal gastric tissues (P<0.05).Conclusion Up-regulation of Notchl and down-regulation of NUMB may play an important role in the occurrence and development of gastric cancer.