Introduction. To report a live birth following egg retrieval after only 12 hours from hCG priming. Patients. A childless couple with five-years-lasting secondary infertility. Methods. IVF was performed according to the long protocol. Two immature oocytes were retrieved following only 12 hours after hCG priming due to the patient misunderstanding. The eggs were cultured in vitro and ICSI was performed following polar body extruded after 24 hours in culture. After additional 24 hours a 4-cell embryo was developed and ET was performed. Results. A viable pregnancy was achieved and a healthy baby girl was delivered at 38 weeks of gestation. Conclusion. In a rare and unexpected situation when immature oocytes are retrieved following a short hCG priming, the eggs should be cultured in vitro, late ICSI should be performed, and a pregnancy may be expected.