Abstract: Objective 　To evaluate the effects of small interfering RNA( siRNA) against either the template RNA (hTR) or it s catalytic subunit (hTERT) of telomerase gene on the proliferation and apoptosis of human renal carcinoma cell line 786-0 cells. Methods 　786-0 cells were t ransfected with hTR-siRNA or hTERT-siRNA (100nmol/ L) . The mRNA expression of hTR and hTERT was detected by RT-PCR. The telomerase activity was detected by telomeric repeat amplification protocol ( TRAP) . The proliferation of 786-0 cells was detected by MTT assay. The apoptosis of 786-0 cells was detected by TUNEL assay. Results 　The hTR and hTERT expression levels of 786-0 cells were reduced significantly by hTR-siRNA and hTERT-siRNA respectively.Both types of siRNA reduced telomerase activity, inhibited proliferation and increased apoptosis of 786-0 cells. When cells were t reated with both hTR-siRNA and hTERT-siRNA simultaneously, the effects did not exceed that seen with each separately. Conclusion 　siRNA against hTR or hTERT gene can inhibit the proliferation and induce apoptosis by blocking telomerase activity of human renalcarcinoma 786-0 cells. The inhibition of telomerase by siRNA may be a rational approach in gene therapy for renal cancer.