Abstract Study question Does male sexual abstinence affect clinical outcomes in oocyte autologous and donation cycles? Summary answer A reduced sexual abstinence period significantly improved ongoing pregnancy rates in oocyte donation cycles What is known already Among various factors affecting sperm quality, the period of sexual abstinence is often overlooked. The World Health Organization (WHO) has established specific standards for sperm analysis and advocates 2-7 days abstinence prior to ejaculation. Other guidelines (ESHRE and NAFA) limit this time to a shorter interval of 3-4 days. Studies suggest that a shorter abstinence period may reduce oxidative stress and improve motile sperm count. However, there is still no consensus on the optimal period of sexual abstinence for achieving the best clinical outcomes when undergoing assisted reproduction techniques (ART). Study design, size, duration Retrospective, single-centre study including 479 ICSI cycles (January 2018 to December 2021). First embryo transfer of the first cycle per patient for both autologous (n = 217) and donor (n = 38) oocyte cycles were analysed. Preimplantation Genetic Testing cycles and those employing microfluidic devices for sperm preparation were excluded as well as patients with abnormal karyotypes, uterine abnormalities and evidence of chronic infectious diseases (Hepatitis B, C or HIV). Participants/materials, setting, methods All cycles used male partner sperm. Two abstinence periods were compared: short (≤ 2 days, n = 108 and n = 16) or long (≥ 3 days, n = 109 and n = 22) for autologous and donor oocytes, respectively. Outcomes considered: seminal parameters; fertilized, 1PN, 3PN, >3PN and degenerated oocytes; implantation and ongoing pregnancy rates. Analysis of variance, Chi-square test and student t-test (Mann Whitney) were used to calculate p-values. A p-value of < 0.05 was considered significant. Main results and the role of chance Mean paternal age was 34.9 and 35.2 years for autologous and oocyte donor cycles, respectively. Regarding sperm parameters, a significant increase in concentration was seen in the long abstinence group (p = 0.009). There was a trend towards improved fertilization and implantation rates in the short abstinence group and also towards lower rates of 1PN, 3PN, >3PN and degenerated oocytes in oocyte donation cycles. Moreover, oocyte donation cycles linked to short abstinence, showed significantly higher ongoing pregnancy rates compared to those involving a long abstinence period (p = 0.015). A similar trend was observed in autologous cycles. Limitations, reasons for caution The small sample size and retrospective design warrant careful interpretation. Wider implications of the findings Our findings suggest that the length of sexual abstinence may have an impact on sperm quality and clinical outcomes. Reduced abstinence may improve ongoing pregnancy rates, potentially due to reduced levels of sperm DNA fragementation. New criteria for abstinence periods should be considered. Trial registration number not applicable