Institutional review board approval was obtained. Children ages 5-18 years old referred to the pediatric urology clinic for primary nocturnal enuresis will be screened for enrollment. Behavioral modification (limiting evening drinking, double voiding prior to bedtime, bowel habits, social anxiety factors) will be utilized first. Patients who fail will next be offered therapy with a bedwetting alarm device or a TENS unit as an alternative, and those who chose TENS therapy will be included in the study. Patients who have previously tried pharmacologic treatment for nocturnal enuresis or alternative therapy for urologic disorders within the past 30 days, daytime incontinence symptoms, known "high volume" voiders (determined from history), bedwetting episodes on the average of less than one time per week, medications predisposing to incontinence (eg, Lithium for bipolar disorder), other known voiding or neurologic disorders (eg, overactive bladder, myelomeningocele), secondary etiologies for nocturnal enuresis (eg, cystitis, obstructive sleep apnea, urinary fistulae), prior use of a TENS unit or other neuromodulation for bedwetting, and any contraindications to usage of a TENS unit such as having a pacemaker will be excluded. Patients who have previously tried the bedwetting alarm will not be excluded from the study.

The patients will be randomized into three groups of 30 patients each. Group 1 will be the long frequency set at 2 Hz. Group 2 will be the moderate frequency set at 10 Hz. Group 3 will be the short frequency set 150 Hz. There is no sham group in this study as the investigator has previously found posterior tibial TENS to be effective and lasting, and as such all patients will be treated. The investigator will aim to recruit 30 patients per group for a total of 90 patients. Detailed explanation of the purpose if the study, along with the risks and benefits of TENS will be given to the patient and caretakers by a provider prior to obtaining informed consent for enrollment into the study. The patients will be provided with a TENS unit and electrode pads and caretakers instructed on how to use the apparatus.

Parents/patients of enrolled patients will fill out nightly voiding diaries, recording nighttime incontinence episodes and subjective "wet sheets" scale per night (dry, damp, wet, soaked) for 30 days prior to randomization into the treatment arms. The TENS sessions will be performed nightly at bedtime for 15 minutes for 30 days. TENS units will be set at a frequency of 10Hz, and intensity determined in the office by the sensitivity threshold of the patient. Voiding diaries will be kept each night while on TENS therapy. A voiding diary will also be completed 30 days before TENS treatment, patients and families will fill out the Pediatric Urinary Incontinence Questionnaire (PIN-Q), a validated tool for measuring quality of life in children with bladder dysfunction. Patients will follow up at day 30 and as needed (worsening symptoms, adverse reactions, concerns, and questions regarding usage of TENS). Patients who record 2 wet nights per week (a total of 8/30=27% wet nights) will be eligible for the TENS study. Those who record less than 2 wet nights per week will be ineligible for the TENS study but will be offered therapy using a bedwetting alarm device or other treatment.