Cyclophosphamide (CP) has been used for over 40 years in patients with steroid-sensitive nephrotic syndrome (SSNS) presenting frequent relapses or steroid dependence (SD). We evaluated retrospectively and tried to identify parameters possibly associated with a prolonged and sustained remission (PSR+) ≥5 years in 108 children with steroid-dependent nephrotic syndrome (SDNS) treated with oral CP. Patients had a follow-up time ≥5 years and were divided into two groups according to achievement of PSR (+ and -). Gender, histological injury, cumulative doses of CP, age of onset of illness, and start of treatment and prednisone dose on the occasion of relapse were analyzed. The overall cumulative sustained remission for 5 and 10 years was 25 and 21.6%, respectively. The only factor that influenced a PSR was the degree of SD: the group PSR+ relapsed at prednisone dose of 0.96 ± 0.51 mg/kg vs. 1.29 ± 0.59 mg/kg in group PSR- (p = 0.01). Also, patients who relapsed in the presence of prednisone doses ≤1.4 mg/kg showed a cumulative sustained remission of 43, 35, and 32.7% at 2, 5, and 10 years, respectively, versus 22.5, 12.5, and 5% in those with prednisone >1.4 mg/kg (p = 0.001). Our findings suggest that patients with SDNS who relapse on prednisone dose >1.4 mg/kg are especially prone to an unfavorable response to CP use.