BACKGROUND: Recurrence of non-muscle-invasive bladder cancer (NMIBC) is common after transurethral resection of bladder tumour (TURBT). Photodynamic diagnosis (PDD) may reduce recurrence. PDD uses a photosensitiser in the bladder that causes the tumour to fluoresce to guide resection. PDD provides better diagnostic accuracy and allows more complete tumour resection. OBJECTIVE: To estimate the economic efficiency of PDD-guided TURBT (PDD-TURBT) in comparison to white light-guided TURNT (WL-TURBT) in individuals with a suspected first diagnosis of NMIBC at intermediate or high risk of recurrence on the basis of routine visual assessment before being scheduled for TURBT. DESIGN SETTING AND PARTICIPANTS: This is a health economic evaluation alongside a pragmatic, open-label, parallel-group randomised trial from a societal perspective. A total of 493 participants (aged ≥16 yr) were randomly allocated to PDD-TURBT (n = 244) or WL-TURBT (n = 249) in 22 UK National Health Service hospitals. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Cost effectiveness ratios were based on the use of health care resources associated with PDD-TURBT and WL-TURBT and quality-adjusted life years (QALYs) gained within the trial. Uncertainties in key parameters were assessed using sensitivity analyses. RESULTS AND LIMITATIONS: On the basis of the use of resources driven by the trial protocol, the incremental cost effectiveness of PDD-TURBT in comparison to WL-TURBT was not cost saving. At 3 yr, the total cost was £12 881 for PDD-TURBT and £12 005 for WL-TURBT. QALYs at three years were 2.087 for PDD-TURBT and 2.094 for WL-TURBT. The probability that PDD-TURBT is cost effective was never >30% above the range of societal cost-effectiveness thresholds. CONCLUSIONS: There was no evidence of a difference in either costs or QALYs over 3-yr follow-up between PDD-TURBT and WL-TURBT in individuals with suspected intermediate- or high-risk NMIBC. PDD-TURBT is not supported for the management of primary intermediate- or high-risk NMIBC. PATIENT SUMMARY: We assessed overall costs for two approaches for removal of bladder tumours in noninvasive cancer and measured quality-adjusted life years gained for each. We found that use of a photosensitiser in the bladder was not more cost effective than use of white light only during tumour removal.