We synthesized a 15-amino acid bi-functional synthetic peptide, RPC2, with the sequence Ac-CGKRKWSQ PKKKRKV-Cysteamide, which consists of a 7-amino acid nuclear localization signal (NLS) domain at the carboxyl terminus that electrostatically binds DNA and a 5-amino-acid tumor-homing domain at the amino terminus. This peptide efficiently delivered GFP and Renilla luciferase reporter genes into rat primary osteoblastic cells while exhibiting low cytotoxicity. The optimal delivery was achieved when the ratio of DNA: RPC2 reached 1:10 (w/w). Transfection efficiency can be further enhanced by the addition of Lipofectamine 2000 and modification of RPC2. These results indicated that RPC2 can deliver exogenous DNA into primary osteoblastic cells with low cytotoxicity and be potentially utilized in experimental and clinical applications in the field of bone tissue engineering.