Purpose: We evaluated the effect of cyclophosphamide pulsetherapy (CYP) combined with prednisolone in progressive primary IgA-nephropathy (IgAN) without extracapillary crescents in 21 patients between 1995 and 2001.Methods: Twenty-one patients (mean age:52 yr SD ± 10.4 yr; M:F 20:1) were treated with serum-creatinine > 175 µmol/l and / or an increase of serum-creatinine more than 25 percent in three previous months indicating a progressive IgAN.Six CYP were given adapted to leukocyte count monthly (750-800 mg/m 2 BSA).CYP were accompanied by an i.v.single dose of 50 mg prednisolone followed by 5-10 mg oral prednisolone.All except one received ACE-inhibitors before and during therapy.The course of renal function was analysed by reciprocal serum-creatinine and linear regression-model.Results: The median time of observation was 3.4 yr (0.5-13 yr).The monthly loss of renal function was reduced significantly (p = 0.002) before therapy from 1.09 percent (0.023 to 9.3) to 0.23 percent (-0.91 to 1.30) after therapy.No significant differences were found between proteinuria, serumprotein, blood pressure, and body-mass index before and after treatment.Conclusion: In progressive IgAN, six cyclophosphamide pulses decelerate the loss of renal function.