AIM: To compare the outcomes achieved with external dacryocystorhinostomy (EX-DCR) and transcanalicular dacryocystorhinostomy (TC-DCR) using a multidiode laser in patients with bilateral nasolacrimal duct obstruction (NLDO). METHODS: This prospective study was conducted on 38 eyes of 19 patients with bilateral NLDO. Simultaneous bilateral surgery was performed on all patients. TC-DCR (Group 1) with a diode laser was used in the right eye, and EX-DCR (Group 2) was used in the left eye. All patients were placed under general anesthesia. Routine follow-ups were scheduled at 1wk; 1, 3, 6 and 12mo postoperative intervals. Objective (lacrimal system irrigation) and subjective [tearing, irritation, pain, discharge and visual analogue scale (VAS) score] outcomes were evaluated. RESULTS: The overall objective success rate at 12mo was 73.7% (14/19) in Group 1 and 89.5 % (17/19) in Group 2. This difference was statistically significant. There were no significant between-group differences in the subjective results, such as tearing, pain and irritation. Only the discharge scores were found to be significantly higher in Group 1 compared to Group 2 at the 1y follow-up. The average VAS score was 6.8 in Group 1 and 8.7 in Group 2, with no statistically significant differences. CONCLUSION: Although TC-DCR allows surgeons to perform a minimally invasive and safe procedure, EX-DCR offers better objective and subjective outcomes than TC-DCR.