Introduction. The diagnosis of detrusor-external sphincter dyssynergia (DESD) is a clinically relevant finding during urodynamic testing. However, there is no consensus regarding diagnostic specifics of electromyography (EMG) or voiding cystourethrography (VCUG). We evaluated the concordance of the two modalities most commonly used in clinical practice for the diagnosis of DESD. Methods. Patients were prospectively evaluated by a single urodynamicist at an academic center and retrospectively re-evaluated by an independent urodynamicist for agreement. DESD was determined by increased patch EMG activity or a dilated bladder neck/proximal urethra on VCUG during detrusor contraction. Minimal acceptable criterion for agreement was set at 70%. Results. Forty-six patients were diagnosed with DESD with both modalities available. Of these 46 patients, 25 were diagnosed by both tests, 11 by VCUG alone and 10 by patch EMG alone. Binomial testing demonstrated the proportion of agreement was 54% (95% CI 39% to 68%). Conclusion. We found significant disagreement between the two modalities, similar to previously reported findings using needle EMG, and we expand the applicability of our data to the majority of clinicians who use patch EMG electrodes. This further supports the idea that the combined use of EMG and VCUG for diagnosis can identify more cases of DESD than either modality alone.