Retroperitoneal fibrosis is a disease with replacement of normal retroperitoneal tissue with isolated fibrotic plaque placed around aorta and entrapping ureters. In 15% of patients an fibrotic process can be found outside the retroperitoneum. The most common localisation outside retroperitoneum is mediastinum, however, it can occur in every organ. The patient usually is diagnosed due to symptoms connected to compression of the ureters. We report the case of 41-year-old woman with chronic obstructive pulmonary disease complaining of nonspecific, dull, noncolicky pain localized to the back and abdomen. Finally we recognised retroperitoneal fibrosis. The diagnosis was proven by lumbar mass biopsy.