Paraplegic spina bifida patients often suffer from disturbed sweat secretion in the paretic regions. A diminished sweat production of caudal parts of the body is compensated by an increased secretion of sweat in parts cranial to the lesion to maintain temperature homoeostais. If the sweat secretion is blocked by anticholinergic effects of urotherapeutic drugs (for instance oxybutynin) hyperthermia can result as a side effect as these casuistic examples show.An 8-year-old girl with a lumbar meningomyelocele and a neurogenic bladder reported a dry skin and hyperthermia up to 38,5°C during oral therapy with oxybutynin (0.4 mg per kg body weight) during hot summer days. Similar symptoms were shown by a 7-year-old male patient with a sacral meningomyelocele and neurogenic bladder on oral therapy of 0.35 mg oxybutynin per kg body weight. A 4-year-old female patient with lumbar spina bifida and neurogenic bladder reacted to intravesical administration of 0.4 and 0.3 mg per kg body weight during early summertime with hyperthermia up to 38°C. In this case the medication had been started in wintertime and was primarily well tolerated.Hyperthermia under treatment with anticholinergic drugs has mainly been published for geriatric patients with sometimes fatal outcome. In the pediatric literature there is only one warning regarding the use of oxybutynin in children with spina bifida living in high temperature regions. It is remarkable that hyperthermia can also happen after intravesical administration of oxybutynin in usual dosage.