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Objectives: To evaluate the feasibilty and detection rate of flexible PDD cystoscopy. Methods: In total 30 patients were included in this two-center study. A flexible endoscope and a rigid instrument were both used in the same patient. In preparation for PDD Hexylaminolevulinate was used. In every patient an experienced surgeon performed the examination of the bladder in white light and PDD using initially a rigid instrument first. Then another blinded surgeon performed a flexible cystoscopy using WL and PDD in the same patient again. In all patients a TUR-BT or bladder biopsy was performed during the same procedure. Results: In all 30 patients flexible cystoscopy could be performed without any technical problems. In the WL setting the overall sensitivity for flexible cystoscopy were 92% (22/24) vs 83% (20/24) using the rigid endoscope. The specificity was 50% for flexible WL vs 33% for rigid WL endoscopy. The accuracy of flexible WL was higher (83%) compared to rigid (73%) cystoscopy. There was an accordance of the two methods of 83% (25/30) with a Cohen´s kappa of k=0.44 (p=0.007). Respecting the data that were acquired in PDD mode only, there was no difference in sensitivity, specificity and accuracy between the two methods (p<0.001). In 24/30 cases there was observed no difference between flexible and rigid cystoscopy regarding fluorescence intensity. Conclusions: Flexible PDD using the chip on the tip technology was feasible with an excellent fluorescence quality. Sensitivity and specificity of flexible PDD was equivalent to the current gold standard - the rigid blue light endoscopy.