Background Very limited data are available on factors predictive of corticosteroids plus cyclophosphamide treatment efficacy on IgA nephropathy (IgAN). The aim of the study was to research the clinical factors predictive of treatment efficacy in IgAN. Methods One hundred and fifty-nine patients with IgAN (proteinuria >= 2g/d and estimated glomerular filtration rate 30-89 ml.min(-1.)1.73 m(-2)) were treated with corticosteroids/cyclophosphamide followed by a 12-month follow-up. According to their response, these patients were divided into remission group (proteinuria <0.5 g/d) and non-remission group (proteinuria >= 0.5g/d), and their clinical data collected. Results In the present study, 72.96% of the individuals underwent a complete remission, and their response was related to baseline proteinuria, urinary osmotic pressure, and renal function (P < 0.05). Patients with baseline proteinuria more than 3 g/d, urinary osmotic pressure greater than 600 mOsm/L, and eGFR 60-89 ml.min(-1).1.73 m(-2) responded well to the combination of corticosteroids and cyclophosphamide (86.90% vs. 57.33%, P=0.000; 81.48% vs. 64.10%, P=0.014; 83.17% vs. 55.17%, P=0.000). Conclusion The response to the combination of corticosteroids and cyclophosphamide might be well associated with baseline proteinuria, urinary osmotic pressure, and renal function in patients with IgAN.