Objectives: To assess the safety and the effectiveness of bipolar energy in the transurethral resection of primary large bladder tumours (TURBT) and compare it to conventional monopolar energy. Patients and methods: From November 2015 to June 2017, 80 patients underwent endoscopic resection primarily for large bladder cancer tumours of >3 cm. They were randomly assigned into two groups: 40 patients underwent a TURBT with conventional monopolar current (M-TURBT) and 40 were treated with bipolar current (B-TURBT). Results: There were no statistically significant differences between the two groups for the patients' demographic and tumour characteristics. There was a significant difference between M-TURBT and B-TURBT for resection time, obturator reflex, hospital stay, and catheterisation time, which were all higher in the M-TURBT group; the mean (SD) resection time was 26.45 (5.73) vs 22.85 (7.52) min (P = 0.048), the obturator reflex was 25% vs 5% (P = 0.025), the median hospital stay and catheterisation times were 2 vs 1 day (P = 0.012 and P = 0.023, respectively). No statistically significant difference was found between the groups for bladder perforation, TUR syndrome, drop in haemoglobin level, and blood transfusion rate. However, there was statically significant difference in the postoperative haematuria rate, which was higher in the M-TURBT group, at 24 patients vs eight in the B-TURBT group (60% vs 20%; P = 0.01). After 1-year follow-up, there was no significant difference in the recurrence rate between the groups. Conclusion: B-TURBT is a safe and effective alternative procedure to M-TURBT for the management of primary large bladder tumours of >3 cm.