© The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. STUDY QUESTIONS: Does polycystic ovarian syndrome (PCOS) or in vitro maturation (IVM) treatment affect embryo development events and morphokinetic parameters after time-lapse incubation? SUMMARY ANSWER: There was an increase in some abnormal phenotypic events in PCOS-IVM embryos as well as an increase in early arrest of PCOS-IVM and PCOS-ICSI embryos; however, IVM treatment or PCOS status did not alter morphokinetic development of embryos suitable for transfer of vitrification. WHAT IS KNOWN ALREADY: IVM has been less successful than standard IVF in terms of clinical pregnancy, implantation and live birth rates. There is currently no information available about the development of IVM embryos according to time-lapse analysis. STUDY DESIGN, SIZE AND DURATION: This article represents a prospective case-control study. The study involved 93 participants who underwent 93 treatment cycles. Cycles were completed between January 2013 and July 2014. PARTICIPANTS/MATERIALS, SETTING AND METHODS: Participants were recruited for the study at Fertility Specialists of WA and Fertility Specialists South, Perth, Western Australia. Of the PCOS diagnosed patients, 32 underwent IVM treatment (PCOS-IVM) and 23 had standard ICSI treatment (PCOS-ICSI). There were 38 patients without PCOS who underwent standard ICSI treatment comprising the control group (control-ICSI). MAIN RESULTS AND THE ROLE OF CHANCE: The PCOS-IVM group showed significantly more embryos with multinucleated two cells (P = 0.041), multinucleated four cells (P = 0.001) and uneven two cells (P = 0.033) compared with the control-ICSI group, but not the PCOS-ICSI group. There were no significant differences in the rates of any abnormal events between the PCOS-ICSI and control-ICSI groups. Embryo arrest between Days 2 and 3 was higher in the PCOS-IVM and PCOS-ICSI groups compared with the control-ICSI group (P <0.001 and P = 0.001). Embryo arrest from Days 3 to 4 was higher in the PCOS-IVM group compared with both the PCOS-ICSI and control-ICSI groups (P <0.001). There were no differences in embryo arrest rates across all three groups at the compaction or blastulation stages. Cumulative rates of embryo arrest, from the time to second polar body extrusion (tPB2) to the time to formation of a blastocyst (tB), result in a decreased proportion of useable PCOS-IVM blastocysts compared with the other two treatment groups; however, of the embryos remaining, there was no significant difference in morphokinetic development between the three groups. LIMITATIONS AND REASONS FOR CAUTION: This was a small study using time-lapse analysis of embryo development as the primary end-point. Larger, randomized, clinical trials are required to clarify the implications of time-lapse incubation of IVM embryos and the effects on implantation and ongoing pregnancy. WIDER IMPLICATIONS OF THE FINDINGS: This is the first study to compare the time-lapse analysis of IVM with standard ICSI for patients with and without PCOS. This allows for a more detailed and specific timeline of events from embryos generated using this approach for patients diagnosed with PCOS and shows that embryos generated from IVM have an increased rate of early embryo arrest, however; morphokinetic development is not impaired in embryos that progress to the useable blastocyst stage. STUDY FUNDING/COMPETING INTEREST(S): The study was supported by the Women's and Infant's Research Foundation of Western Australia. R.H. is the Medical Director of Fertility Specialists of Western Australia and a shareholder in Western IVF. He has received educational sponsorship from MSD, Merck-Serono and Ferring Pharmaceuticals. The other authors have no competing interests.