AIM: IgA nephropathy (IgAN) is a very common glomerulonephritis among young adults, but the best therapeutic approach has not been fully elucidated. This study evaluated the effect of two different treatment regimes in IgAN, steroids alone or in combination with azathioprine.METHODS: Among 122 patients with primary IgA nephropathy diagnosed in the 2000-2007 period, 22 fulfilled the inclusion criteria for the study: estimated glomerular filtration rate (eGRF) ≥30 ml/min/1.73 m(2), urine protein (Upr) ≥1 g/24 h, blood pressure (BP) <130/80 mmHg, and previous treatment with renin-angiotensin system inhibitors (RAASi) and polyunsaturated fatty acids (PFA) for at least 6 months. Patients were randomized to receive either methylprednisolone alone (MP group) or MP in combination with azathioprine (MP + Aza group) for 12 months, while treatment with RAASi + PFA continued unchanged in both groups.RESULTS: At the completion of the trial, renal function in the MP group remained stable, eGFR from 52 ± 26.7 to 53.6 ± 27.3 ml/min/1.73 m(2), p = NS, and Upr decreased from 2.4 ± 0.9 to 0.8 ± 0.5 g/24 h, p < 0.001. In the MP + Aza group, eGFR slightly increased from 57.4 ± 28.7 to 66 ± 31 ml/min/1.73 m(2), p = NS, and Upr decreased from 2.4 ± 1 to 0.7 ± 0.7 g/24 h, p < 0.001. Four patients from the MP group with partial remission at the end of the trial had a complete response when converted to Aza. Eleven patients (5 from the MP and 6 from the MP + Aza group) relapsed after stopping treatment and were restarted on lower doses.CONCLUSIONS: Both, steroid treatment alone and steroids in combination with azathioprine seem to be effective in reducing the severity of proteinuria and stabilizing renal function in IgAN. Patients who do not respond to steroids may have a better response with the combination of steroids and azathioprine.