Two shRNA sequences against porcine somatostatin (SST) were designed using software available on the NCBI website. The designed RNA sequences were chemically synthesized and cloned into lentiviral vectors (LV-siRNA1 and LV-siRNA2). Porcine somatostatin cDNA was amplified and cloned into pcDNA3.1 (pcDNA3.1-SST). LV-siRNA1 or LV-siRNA2 was cotransfected with pcDNA3.1-SST into NIH3T3 cells. Real-time RT-PCR for the detection of SST mRNA, revealed that LV-siRNA1 and LV-siRNA2 suppressed SST expression by 87.9% and 86.3% (P < 0.01), respectively. In addition, radioimmunoassay (RIA) for direct detection of SST indicated that the suppression ratios for LV-siRNA1 and LV-siRNA2 were 55.1% and 51.6% (P < 0.01), respectively. These data showed that the 2 shRNA sequences were effective in suppressing SST expression and may provide an approach to down-regulate both in vitro and in vivo expression of porcine SST.