PURPOSE We evaluated the clinical use of air cystoscopy, including its possible advantages and disadvantages over water cystoscopy. MATERIALS AND METHODS Two independent observers prospectively studied consecutive patients who underwent water cystoscopy first and then air cystoscopy at our center from May to September 2012. The indication for rigid cystoscopy in the operating room was noted independently by either observer. Findings after rigid cystoscopy were correlated with the results of flexible water and air cystoscopy using the Pearson correlation and Student t-test. RESULTS Included in the study were 57 patients with active hematuria, of whom 36 had bladder cancer, and 257 with a history of bladder tumor. The cause of bleeding was clearly identified on water cystoscopy in 22 patients (38%), including tumors in 17 and prostate bleeding in 5, and by air cystoscopy in 49 (86%), including tumors in 32 and prostate bleeding in 17. For diagnosing bladder tumors air cystoscopy had higher sensitivity than water cystoscopy (88% vs 47%, p=0.003) and similar specificity (97% vs 100%, p=0.93). In the 295 patients without hematuria there was no difference in the indication compared to that identified on rigid cystoscopy (43 vs 43, p=1.0). Water cystoscopy revealed more small papillary tumors than air cystoscopy but the number was not significantly different (76 vs 67, p=0.26). All such implants identified on water cystoscopy alone were less than 2 mm. No complication specifically related to air cystoscopy was noted. CONCLUSIONS We found no statistical difference between water and air cystoscopy in patients without hematuria. Air cystoscopy had higher sensitivity and specificity for diagnosing active hematuria while adding almost no specific complications to the procedure.