Here, we compared the effects of bipolar and monopolar transurethral resection of the prostate (B-TURP, M-TURP) for treating elderly patients (≥75 years) with benign prostatic hyperplasia(BPH) who had internal comorbidities. Eligible BPH patients were aged ≥75 years and had at least one internal comorbidity. In this open-label, prospective trial, patients were assigned to B-TURP (n = 75) and M-TURP (n = 88) groups. Data on prostate volume (PV), urination, and time during perioperative period were compared; data associated with urination and complications at one year postoperatively were also compared. Finally, follow-up data were available for 68 and 81 patients in the B-TURP and M-TURP group, respectively. No deaths were recorded. Intraoperative bleeding was lower and irrigation time, indwelling catheter time, and hospital stay were shorter in the B-TURP group than in the M-TURP group (p < 0.001). No difference was observed with respect to operation time (p = 0.058). At one year after the operation, differences with respect to urination and complications were not significant. In conclusion, Short-term efficacy of B-TURP or M-TURP was satisfactory for elderly patients with BPH who had internal comorbidities. Besides, B-TURP is a more sensible choice because it has a lower prevalence of adverse effects.