Focal and segmental glomerulosclerosis (FSGS) is a heterogeneous entity. Previous few studies have evaluated the efficacy of calcineurin inhibitors in primary FSGS and have suggested positive benefit. In this single-center, retrospective study (1975-2014), we report our experience in Tunisian adults with primary FSGS treated with cyclosporine A (CsA). It includes patients histologically proven FSGS and managed in the Charles Nicolle Hospital at Tunis, Tunisia. The dose of CsA was adjusted to maintain a whole blood trough level of 80-150 ng/mL. The observation period was 6.8 ± 3.7 years after CsA treatment. Twenty-three patients with idiopathic FSGS, treated with CsA, were studied. The mean age was 26.69 ± 10.1 years, and the sex ratio was 2.83. Eight patients (35%) had a steroid-dependent nephrotic syndrome (NS), and 15 patients (65%) had for steroid-resistant NS. After a median follow-up of 16.5 months on CsA, we noticed complete remission of the NS in eight cases (35%) after 12.12 ± 8 months, partial remission in five (22%) after 3 ± 0.7 months, dose-dependent remission to CsA (2.87 mg/kg/day) in four (17%), and a no response in six patients (26%). Eleven patients (48%) showed improvement of renal function, while eight (35%) developed end-stage renal disease (ESRD) after 35.7 ± 20.9 months. Predictive factors of progression to ESRD were creatinine clearance <90 mL/min before introduction of CsA (P = 0.0054) and CsA-resistance (P = 0.053). Our study suggests that CsA is effective in the treatment of patients with idiopathic FSGS. Initial renal function and cyclosporineresistance are the predictive factors of ESRD in steroid-resistant or -dependent FSGS.