Background Cerebrospinal fluid (CSF) leaks can be associated with significant morbidity such as meningitis. Surgical management has proven effective, with endoscopic approaches having become the gold standard due to success rates >90%. Inability to localise the leak site prior to surgery is associated with surgical failure. The use of intrathecal fluorescein (IF) to localise CSF fistulae sites was first demonstrated in 1960. Despite this, its use in this context is unlicensed. Objective Evaluate the safety and efficacy of IF use in the management of CSF leak repairs in our centre. Methods All patients who underwent endoscopic repair of CSF fistula by a single surgeon where IF was used between January 2010 – September 2019 at a single-centre (tertiary skull base referral unit in the United Kingdom) were retrospectively analysed. Primary outcome measures were localisation of CSF fistula with IF (efficacy) and peri-operative complications likely to be attributable to IF (safety). Results There were 55 patients included (60 procedures) with a positive localisation rate of 90.0% with IF. The overall peri-operative complication rate was 8.3% (n = 5). It is likely that none were related to IF use. However, three complications may be linked giving a complication rate potentially related to IF of 5.0%. There were no peri-operative mortalities. Conclusion Many studies have demonstrated IF to be safe at low doses (<50mg) with a high sensitivity, specificity and positive predicative value. Our results demonstrate that the use of IF in our centre is safe and effective at identifying CSF fistulae. While we have reported some complications in our cohort, these were unlikely to be directly attributable IF use. We have described no serious complications such as seizures, limb weakness or death. We believe this study adds to the growing body of evidence that IF use in the management CSF fistula repairs is safe and effective.