There is a paucity of high quality evidence regarding the routine placement of lumbar drain (LD) in reducing post-operative (op) cerebrospinal fluid (CSF) leak after extended endoscopic trans-sphenoidal resection of anterior skull base lesions. In this study, we sought to compare the incidence of post-op CSF leak between patients with upfront LD insertion and those without it. This was a prospective randomized controlled trial conducted over a period of 5 years with patients undergoing extended endoscopic trans-sphenoidal surgery randomly assigned to either LD insertion at the time of surgery, or no LD placement. Thirty-eight patients with anterior skull base tumors were accrued from three tertiary hospitals of Melbourne. Post-op leak was confirmed by β2-transferrin-positive rhinorrhea, and/or worsening pneumocephalus on brain imaging. Skull base defect size and pedicled nasoseptal flap viability were assessed on post-op CT and MRI, respectively. There was no significant difference in post-op CSF leak incidence between the two subgroups (12.50% in LD arm vs. 9.10% in no LD arm). Patients with LD insertion however, demonstrated substantially raised complication rates, longer hospital lengths of stay and lower subjective quality of life measures at 12 months compared with those without LD. In conclusion, routine placement of LD at the time of surgery for extended anterior skull base trans-nasal approach did not reduce the risk of post-op CSF leak. Discretion is warranted when using LD as an adjunct due to its associated morbidities, prolonged hospital stay and adverse effect on patients’ subjective outcome measures.