A 33-year-old man presented with lymphoedema and obstructive nephropathy and was first diagnosed as retroperitoneal fibrosis (RF) with consistent clinical picture and radiographic findings. Further CT-guided biopsy was performed and non-Hodgkin lymphoma was diagnosed based on pathological results. RF is usually diagnosed through clinical presentation and imaging studies. However, our case proved that biopsy should be considered to exclude malignancy, even with typical presentations of RF. Follow-up after six courses of R-CHOP (rituximab, cyclophosphamide, vindesine, epirubicin and prednisone) regimen revealed complete resolution of symptoms.