Objective:To detect the human-specific protein kinase-15(NYD-SP15) gene expression in normal gingival tissue and hyperplastic gingival tissues,observe the expression of NYD-SP15 protein in gingival tissues,and to explore the relationship of NYD-SP15 and gingival hyperplasia initially. Methods:Reverse transcription-polymerase chain reaction(RT-PCR) and immunohistochemical method were applicated to detect the expression of NYD-SP15 gene in gingival tissues of 27 cases of normal people and 40 cases of gingival hyperplasia patients. The normal gingival tissues were the excision of gingival tissue during crown lengthening surgery (the teeth were traumatic crown fractures),recorded as normal control group. The hyperplasia samples were the excision of gingival tissue during gingivectomy,recorded as hyperplasia group. The half of all specimens were removed and stored in nitrogen liquid immediately. The remaining half of the tissues with formalin,embedded in paraffin storage. Staining positive cells were counted under the microscope and classificated by positive degree. The data of the experiment was analyzed by Stata 9.2(StataCorporation College Station,TX) software. Results:The expression of NYD-SP15 mRNA in tissues of hyperplasia group was significantly higher than that of control group(P < 0.05). The immunohistochemistry results showed that the NYD-SP15 protein was highly expression in the cytoplasm in normal gingival tissue. But,in the hyplasia gingival tissues,the expression of NYD-SP15 protein was highly in the nucleus. Conclusion:The level of NYD-SP15 expression and location in the gingival tissues may be associated with the gingival hyperplasia. However,the relationship between them remains to be further studied.