The presence of renal noninflammatory necrotizing vasculopathy (NNV) is often associated with a severe form of lupus nephritis (LN), which is unresponsive to standard therapy. We conducted a 6-month randomized, prospective, open-label trial comparing mycophenolate mofetil (MMF) (1.5-2.0 g/day) with monthly i.v. cyclophosphamide (CTX) (0.75-1.0 g/m2) as induction therapy for class IV LN with NNV. The primary and second end points were complete remission (CR) and partial remission (PR), respectively. Of 20 patients recruited, nine were randomly assigned to MMF and 11 to CTX. The baseline characteristics between groups were not significant. CR was achieved in four patients (44.4%) receiving MMF and in none of the patients receiving CTX (P = 0.026). PR was achieved in two patients (22.2%) in the MMF group and three patients (27.2%) in the CTX group. The total remission rate (CR + PR) in the MMF and CTX group was 66.6 and 27.2%, respectively (P = 0.17). MMF was more effective than i.v. CTX in reducing proteinuria and haematuria. Adverse events were significantly less frequent with MMF than with CTX (P = 0.028). MMF was superior to i.v. CTX in inducing CR of LN with NNV and had a more favourable safety profile.