Idiopathic retroperitoneal fibrosis, also known as Ormond’s disease, can present as an IgG4-related disease involving the deposition of fibrous tissue in the retroperitoneal space. It is caused by chronic inflammation developing around the abdominal aorta and common iliac arteries. The case report describes a patient hospitalised for complaints of low back pain with positive Goldflam’s sign and hydronephrosis, whose abdominal CT scan showed a tumour in the retroperitoneal space pressing on the ureter. Based on histopathological examination and laboratory tests, the patient was diagnosed with idiopathic retroperitoneal fibrosis, most likely related to IgG4. After diagnosis, the patient was initially treated in the urology department for urinary retention and then received treatment with glucocorticosteroids, according to the treatment guidelines for IgG4-dependent disease.