The aim of the present study was to investigate the effect of vascular endothelial growth factor (VEGF) on the meiotic and developmental competence of porcine oocytes from small follicles (SF; 0.5-3 mm diameter). When cumulus-oocyte complexes (COCs) from medium-sized follicles (MF; 3-6 mm diameter) and SF were cultured for IVM, the maturation rates were significantly higher for oocytes from MF than SF. Concentrations of VEGF in the medium were significantly higher for COCs cultured from MF than SF. When COCs from SF were exposed to 200 ng mL -1 VEGF during the first 20 h of IVM, the maturation rate improved significantly and was similar to that of oocytes derived from MF. The fertilisability of oocytes was also significantly higher than that of VEGF-free SF controls. Following parthenogenetic activation, the blastocyst formation rate improved significantly when SF COC culture was supplemented with 200 ng mL -1 VEGF, with the rate similar to that of oocytes from MF. The results of the present study indicate that VEGF markedly improves the meiotic and developmental competence of oocytes derived from SF, especially at a concentration of 200 ng mL -1 during the first 20 h of IVM.Additional keyword: pig. T. M. T. Bui et al. Effect of VEGF on IVM of porcine oocytesOvaries contain a large number of small follicles, but the meiotic and developmental competence of oocytes from these follicles is quite low. In the present study we demonstrated that the addition of 200 ng mL -1 vascular endothelial growth factor to the IVM medium increased the maturation rate of porcine oocytes from small follicles and that blastocyst formation following parthenogenetic activation also increased. These findings may contribute to efficient animal production and human assisted reproductive technology.