Medicated-fibers have been obtained through electrospinning after rifampin was dissolved in poly (lactic acid)/chloroform solution. The relationship between polymer variables [such as concentration, molecular weight (Mw), and introducing hydrophilic block] and drug release from the electrospun fibers is disclosed. The results show that polymeric concentration and Mw are crucial for producing the medicated fibers, which influence not only the morphology of the medicated-fiber but also drug release rate from fiber. At the same Mw, the drug release rate decreases with the increase of spinning concentration. At two different Mw blends, drug release behaviors change. When the low Mw content is in a dominant position, drug release rate depends largely on mixing ratio of two Mw contents; on the other hand, drug release rate is also dependent on concentration of spinning fluid. In addition, the block copolymer [poly-L-lactic acid (PLLA)-polyethylene glycol-PLLA] shows faster release rate as compared to homopolymer (PLLA). (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 50: 221-227, 2011