Abstract In this prospective randomized study, the effect of daily gonadotrophin-releasing hormone agonist (GnRHa) in the luteal phase on IVF and intracytoplasmic sperm injection (ICSI) outcomes was assessed. Women (n = 446) were counselled for IVF–ICSI, and randomized on the day of embryo transfer to group 1 (daily 0.1 mg subcutaneous GnRHa until day of beta-HCG) (n = 224) and group 2 (stopped GnRHa on day of HCG injection) (n = 222). Both groups received daily vaginal progesterone suppositories. Primary outcome was clinical pregnancy rate. Secondary outcome was ongoing pregnancy rate beyond 20 weeks. Mean age, oestradiol on day of HCG, number of oocytes retrieved, number of embryos transferred, and clinical and ongoing pregnancy rates were 28.9 ± 4.5 years, 2401 ± 746 pg/mL; 13.5 ± 6.0 oocytes; 2.6 ± 0.6 embryos, and 36.2% and 30.4% consecutively in group 1 compared with 29.7 ± 4.7 years, 2483 ± 867 pg/mL, 13.7 ± 5.5 oocytes, 2.7 ± 0.6 embryos, 30.6% pregnancy rate, and 25.7% ongoing pregnancy rate in group 2. No significant difference was found between the groups. Subcutaneous GnRHa during the luteal phase of long GnRHa protocol cycles does not increase clinical or ongoing pregnancy rates after IVF–ICSI.