BACKGROUND Advances in percutaneous nephrolithotomy (PCNL) have resulted in smaller devices that cause less trauma and bleeding, while flexible ureterorenoscopy (f-URS) allows access to any calyces. These methods are often used in isolation, but used in combination they may improve treatment of complex renal calculi. This study assessed the effectiveness and complications of f-URS combined with super-mini-PCNL (SMP) to treat complex renal calculi. MATERIAL AND METHODS A retrospective cohort analysis was made of patients with unilateral complex renal stones treated between March 2013 and December 2016. Patients were grouped according to surgical procedure: SMP (SMP Group), f-URS holmium laser lithotripsy (f-URS Group), and combined SMP and f-URS (Combined Group). The postoperative complications and complete stone-free rate were analyzed and compared among the 3 groups. RESULTS A total of 140 patients with complex renal stones were included: 40 patients in the SMP Group, 55 in the f-URS Group, and 45 in the Combined Group. The complete stone-free rate 3 days after the procedure was 77.5% in the SMP Group, 78.2% in the f-URS Group, and 97.8% in the Combined Group (p=0.010). The operation time, intraoperative blood loss, and hospitalization time of the Combined Group were all significantly lower than those in the SMP Group but higher than those in the f-URS Group. The follow-up was 9 months (range, 6-12 months). There were no medium-term complications reported. CONCLUSIONS SMP combined with f-URS holmium laser lithotripsy in the prone position is an effective treatment for complex renal calculi.