We report the case of a 56-year-old postmenopausal woman who was referred to our Endocrinology Outpatient Clinic because of severe hyperhidrosis. She had a four-year history of excessive sweating of her face and upper body. On presentation no sweating could be documented. physical examination was also unremarkable. It appeared that five days earlier her general practitioner had prescribed oxybutynin for urge incontinence and this accidentally cured her hyperhidrosis. She was diagnosed with idiopathic hyperhidrosis. We advised her to continue the oxybutynin and six months later, she was still symptom-free. Oral anticholinergic drugs are known to be effective for hyperhidrosis, but only anecdotal reports on oxybutynin can be found in the literature. Oxybutynin is not approved for hyperhidrosis, explaining the unfamiliarity with this medicine. This case shows that oxybutynin can be a very effective and simple treatment with only mild side effects. Therefore, oxybutynin merits consideration in patients with idiopathic hyperhidrosis. This report includes a concise review of the causes and treatment options of hyperhidrosis.