The aim of this study was to confirm the effect of dithiothreitol (DTT)-treated spermatozoa on oocyte activation following intracytoplasmic sperm injection (ICSI). Boar spermatozoa with or without DTT treatment (5 mM, 30 min) were injected into in vitro matured porcine oocytes, and the nuclear phase in presumptive zygotes was observed at 3 h intervals up to 12 h after ICSI. Furthermore, developmental competence of embryos produced by DTT-treated or non-treated spermatozoa was monitored after cultivation in vitro for 144 h. Male and female pronuclear formation rates in the oocytes injected with DTT-treated spermatozoa were significantly (P < 0.05) higher than those in the oocytes injected with non-treated spermatozoa. Additionally, we observed that female pronuclear formation was linked to male pronuclear formation. Sperm treatment with DTT improved (P < 0.05) subsequent development up to the blastocyst stage. These findings confirm the efficiency of DTT in in vitro porcine embryo production mediated by ICSI. We conclude that DTT treatment improves the formation of not only male pronuclei but also female pronuclei in porcine ICSI.