The aim of this study was to analyze the effect of exposure to antimalarial drugs at diagnosis of lupus nephritis on the outcome of the disease, especially renal failure, comorbid processes, and survival. We analyzed a cohort of 206 consecutive patients with biopsy-proven lupus nephritis. Renal biopsies were categorized according to the classification proposed by the ISN/RPS in 2003. Exposure to antimalarial drugs (chloroquine and hydroxychloroquine) was defined as the use of these drugs before the diagnosis of lupus nephritis independent of dose and duration. Fifty-six (27%) patients had received antimalarials before the diagnosis of lupus nephritis. During the follow-up, these patients had a lower frequency of creatinine values >4 mg/dL (2% vs 11%, P = 0.029) and end-stage renal failure (2% vs 11%, P = 0.044) in comparison with those never treated with antimalarials. Patients exposed to antimalarials also had a lower frequency of hypertension (32% vs 50%, P = 0.027), infections (11% vs 29%, P = 0.006), and thrombotic events (5% vs 17%, P = 0.039). Twenty patients (10%) died during the study period. Patients exposed to antimalarials had a lower mortality rate at the end of the follow-up (2% vs 13% for those not exposed to antimalarials, P = 0.029). Multivariate analysis identified thrombosis and infections as statistically significant independent variables. Kaplan-Meier plots showed a lower rate of end-stage renal failure (log rank = 0.04) in patients exposed to antimalarials. In conclusion, exposure to antimalarials before the diagnosis of lupus nephritis was negatively associated with the development of renal failure, hypertension, thrombosis and infection, and with a better survival rate at the end of the follow-up. This, together with other published data, suggests that antimalarials should be considered a mandatory therapeutic option in all patients diagnosed with systemic lupus erythematosus.