The melt-crystallization behaviors of poly (L-lactic acid) (PLLA) in the presence of the external DC electric fields are reported. The real-time monitoring of the melt-crystallizations were provided with polarizing optical microscope at the isothermal crystallization temperatures T-c = 120 - 150 degrees C under the voltages V-DC = 0-200 V. The crystal nucleation took place selectively at the edge of the anodes, and the highly oriented crystals grew in the direction perpendicular to the anode. The nucleation rate in the presence of the fields was much faster than that on the spherulite growth in the absence of the fields. The nucleation rate was also faster as the applied voltages were higher. On the other hand, the crystal growth rate was almost independent of the magnitude of the applied voltage value. The present experimental results indicated that the applications of the electric fields were helpful for accelerating the crystal nucleation rate of the PLLA. (C) 2016 Elsevier Ltd. All rights reserved.