Background: Esophageal intraluminal baseline impedance reflects the conductivity of the esophageal mucosa and may be an instrument for in vivo evaluation of mucosal integrity in children with gastroesophageal reflux disease (GERD). Laparoscopic antireflux surgery (LARS) is a well-established treatment option for children with proton pump inhibitory (PPI) therapy resistant GERD. The effect of LARS in children on baseline impedance has not been studied in detail. The aim of this study was to evaluate the effect of LARS on baseline impedance in children with GERD. Methods: This is a prospective, multicenter, nationwide cohort study (Dutch national trial registry: NTR2934) including 25 patients [12 males, median age 6 (range 2–18) years] with PPI-resistant GERD scheduled to undergo LARS. Twenty-four hour multichannel intraluminal impedance pH monitoring (MII-pH monitoring) was performed before and 3 months after LARS. Baseline impedance was evaluated during consecutive 2-h intervals in the 24-h tracings. Results: LARS reduced acid exposure time from 8.5 % (6.0–16.2 %) to 0.8 % (0.2–2.8 %), p < 0.001. Distal baseline impedance increased after LARS from 2445 Ω (1147–3277 Ω) to 3792 Ω (3087–4700 Ω), p < 0.001. Preoperative baseline impedance strongly correlated with acid exposure time (r −0.76, p < 0.001); however, no association between symptomatic outcome and baseline impedance was identified. Conclusions: LARS significantly increased baseline impedance likely reflecting recovery of mucosal integrity. As the change in baseline impedance was not associated with the clinical outcome of LARS, other factors besides mucosal integrity may contribute to symptom perception in children with GERD