We present the case of a 45-year-old woman presenting with a spontaneous cerebrospinal fluid (CSF) rhinorrhoea. A CSF leak, arising from a posterior ethmoidal left cell, was closed using an underlay procedure with a turbinate composite graft with applied fibrin glue. Twenty-three months later the CSF rhinorrhoea recurred. Recurrence was imputed to morbid obesity (BMI 48) responsible for benign intracranial hypertension. The patient underwent a laparoscopic adjustable gastric banding. CSF rhinorrhoea gradually decreased during the 12 months following surgery, in correlation with the weight loss, until total resolution was achieved. To our knowledge, this is the second reported case of a spontaneous CSF leak treated by bariatric surgery. This observation strengthens the theory that severe obesity can cause benign intracranial hypertension which can lead to CSF leak.