Ovarian hyperstimulation syndrome (OHSS) is a rare complication of controlled ovarian stimulation (COS) in patients undergoing in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Prior to the embryo transfer the risk of OHSS should be assessed for proper management upon incidence of this condition or using prevention guidelines beforehand. This case report presents a case of severe late-onset OHSS in a low-risk 29 years old nulliparous patient. The patient presented with severe abdominal ascites and liver dysfunction. The conservativetreatment contained fluid and electrolyte intake control along with paracentesis of ascites.