In the advent of the recent Bacillus Calmette–Guérin (BCG) crisis, the importance of alternative adjuvant treatments for intermediate- and high-risk non-muscle-invasive bladder cancer (NMIBC) has been highlighted. Chemohyperthermia (CHT) has emerged as an option, however there remains a lack of robust comparative data with BCG. In this multicentre, prospective phase three trial, patients with intermediate- or high-risk papillary NMIBC were randomised to receive either adjuvant CHT with Mitomycin C weekly for six weeks followed by six maintenance sessions during year one, or BCG six weekly induction sessions and three weekly maintenance sessions at months 3, 6 and 12. The trial included 190 patients recruited between 2002 and 2012, however it closed prematurely due to slow accrual. The primary endpoint was 24 months recurrence free survival (RFS). The study identified a significantly higher RFS rate in the CHT with Mitomycin C group compared with BCG in the per-protocol analysis, and although a difference in RFS in favour of CHT with Mitomycin C was noted in the intention to treat analysis, this did not reach statistical significance. The study was unfortunately underpowered due to the premature closing of the trial, and follow-up was limited to two years. Equally the number of patients with high-risk papillary NMIBC excluding CIS (n=15) was low, therefore conclusions in this group cannot be drawn. None the less, CHT with Mitomycin C remains an evolving option, which may be considered should the BCG crisis recur.