Abstract: Objective To investigate the expressions of Ki67, placental alkaline phosphatase (PLAP), cytokeratin (CK)and their diagnostic values to germinomas and pituitary adenomas. Methods Thirty-six patients with germinomas (experiment group) and 40 patients with pituitary adenomas (control group) were selected. The expression of Ki67, PLAP and CK were detected by immunohistochemical assay, and the difference of their expression in two tumors was analyzed. Results The positive rates of Ki67,PLAP in germinomas were significantly higher than those in pituitary adenomas (Ki67:95.2% vs 47.6%, P=0.001; PLAP:88.6% vs 16.7%, P< 0.001). The positive rate of CK in germinomas was 27.8% (5/18), which was significantly lower than that in pituitary adenomas of 82.6% (19/23) (χ²=12.508, P< 0.001). Conclusion Ki67, PLAP and CK can serve as auxiliary biological indicators in differential diagnosis of germinomas and pituitary adenomas.