OBJECTIVE To examine the long-term renal outcomes of systemic lupus erythematosus (SLE) patients with transient proteinuria. METHODS The medical records of SLE patients who showed improvement in proteinuria (urine protein/creatinine ratio < 500 mg/g) after receiving corticosteroid therapy without immunosuppressants were reviewed. RESULTS A total of 38 patients (mean creatinine: 0.74 ± 0.33 mg/dl) showed an improvement of proteinuria (1361 ± 1053 mg/g to 289 ± 125 mg/g) after receiving corticosteroid therapy alone for a median of 25 days (IQR, 10-55). After follow-up (median, 23 months [IQR, 15-121]), 25 (65%) patients maintained the resolution of proteinuria without renal dysfunction. The remaining 13 (34%) patients experienced a relapse of proteinuria during a median follow-up of 13.9 months from baseline (IQR, 1.6-25). There was no significant difference in the baseline laboratory data according to the occurrence of proteinuria relapse, but longer SLE disease duration at baseline was associated with the risk of proteinuria relapse (HR, 1.007; p = 0.033). Of the patients who underwent renal biopsy with proteinuria relapse, class II (53%) lupus nephritis was the most common pathology. None progressed to end-stage renal disease during an additional long-term further follow-up of median 33 months (IQR, 22-49) after proteinuria relapse. CONCLUSIONS Two-thirds of SLE patients who showed improvement in proteinuria after corticosteroid alone maintained the non-proteinuric state without renal dysfunction. Thus, performing a kidney biopsy at the first onset of proteinuria could be delayed in patients who show an improvement in proteinuria after treatment with corticosteroids.