<i>Introduction:</i> Near-infrared spectroscopy (NIRS) is an optical technology able to detect the hemodynamic changes in biological tissues. Our objective was to determine the feasibility of applying NIRS in the noninvasive diagnosis of detrusor overactivity (DO). <i>Patients and Methods:</i> Comparative analysis was performed on 39 involuntary detrusor contractions (IDC) from 23 filling cystometries with simultaneous noninvasive NIRS of the bladder in 14 patients with DO. Motion artifacts were checked for via surface EMG of the abdominal muscles. <i>Results:</i> Thirty-nine IDC were obtained. The median amplitude of rise in detrusor pressure at DO was 48 cm H₂O (range: 5–219). The median filling volume at DO was 148 ml (range: 9–531). NIRS curves demonstrated apparently significant deviations from baseline in 35 of 39 (90%) DO episodes. All onsets of NIRS deviations occurred within the time period of the IDC with a mean delay of 3 s (range: 0–9). <i>Conclusion:</i> NIRS can be a potential tool for the noninvasive diagnosis of DO.