To examine the solvent-free effect in electrospun micro/nanofibers on cellular activities, melt-electrospun poly(lactic acid) (PLA) micro/nanofibers with a diameter of 1.5 +/- 0.8 mm and a randomly distributed mesh structure were successfully fabricated with a gas-assisted melt-electrospinning system. Pre-osteoblast cells (MC3T3-E1) cultured on both solvent-based electrospun (SES) fibers and melt-based electrospun (MES) fibers in osteogenic media differentiated down the osteogenic lineage, considering the bone mineralized protein-2 (BMP-2) and osteocalcin (OCN) gene expressions were significantly increased on the MES fibers compared to the SES fibers. The BMP-2 and OCN expressions from cells on the MES fibers were 6-fold and 1.8-fold greater than those on the SES fibers, respectively, due to the solvent-free condition. In addition, MES fibers provide a significantly high cell-viability approximately 2-fold greater than SES fibers. Based on this work, MES micro/nanofibers can be important biomedical scaffolds for various tissue engineering applications.