The goal of the present work was to characterise morphologically the oocytes and zygotes of Myocastor coypus. In order to obtain the samples, a daily colpocytological follow-up and programmed mating of females were done. By flushing of the oviducts, oocytes (17) and zygotes (24) were collected. In the analysis of the oocytes and zygotes, morphological aspects, including analysis of cellular polarity and of the envelopments were considered. Oocytes presented spherical shape with a cellular diameter of 85.7 ± 3.1 µm. The nucleus presented a diameter of 28 ± 3.1 µm. The occupied perivitelline space was 98%, with a zona pellucida thickness of 15.9 ± 1.9 µm. The existence of ovular polarity was determined. Zygotes presented an external diameter, measured to the zona pellucida, of 125 ± 8.6 mm and an embryonic diameter of 80.6 ± 8.1 µm. In 91.7% of the cases, they were in the stage of 2-nucleus zygote. A homogenous distribution of cytoplasmic granulations was observed in all the zygotes. As the only and complete envelopment, zygotes presented the zona pellucida, obtaining few specimens with associated granulose cells