Polycaprolactone (PCL) and biphasic calcium phosphate (BCP) have been considered as useful materials for orthopedic devices and osseous implants because of their biocompatibility and bone-forming activity. However, PCL-based scaffolds have hydrophobic surfaces reducing initial cell adhesion or proliferation. To overcome the limitation, we fabricated surface-modified PCL/BCP nanofibers using gamma-irradiation for bone tissue engineering. PCL/BCP nanofibers were prepared by electrospinning and then we supplemented hydrophilicity by introducing acrylic acid (AAc) through gamma-irradiation. We confirmed the surface of nanofibers by SEM, and then the initial viability of MG63 was significantly increased on the AAc grafted nanofibers, and alkaline phosphatase activity(1.239 +/- 0.226 nmole/mu g/min) improved on the modified nanofibers than that on the non-modified nanofibers(0.590 +/- 0.286 nmole/mu g/min). Therefore, AAc-grafted nanofibers may be a good tool for bone tissue engineering applications.