BACKGROUND & AIMS: Functional constipation (FC) is a common childhood problem often related to pelvic floor muscle dysfunction. We compared the effectiveness of pelvic physiotherapy (PPT) vs standard medical care (SMC) in children with FC. METHODS: We performed a multicenter randomized controlled trial of 53 children (age, 5-16 y) with FC according to the Rome III criteria, at hospitals in The Netherlands from December 2009 to May 2014. Group allocation was concealed using a central computer system. SMC consisted of education, toilet training, and laxatives (n = 26), whereas PPT included SMC plus specific physiotherapeutic interventions (n = 27). Results were obtained from written reports from the subjects’ pediatricians and parents. The primary outcome was absence of FC, according to Rome III criteria, after a 6-month follow-up period. Secondary outcomes were global perceived effect (range, 1-9; success was defined as a score >/= 8), numeric rating scales assessing quality of life (parent and child; scale, 1-10), and the strengths and difficulties questionnaire (SDQ). RESULTS: Treatment was effective for 92.3% of the children receiving PPT and for 63.0% of the children receiving SMC (adjusted odds ratio for success of PPT, 11.7; 95% confidence interval, 1.8-78.3) (P = .011). Significantly more children undergoing PPT stopped using laxatives (adjusted odds ratio, 6.5; 95% confidence interval, 1.6-26.4) (P = .009). Treatment success (based on global perceived effect) was achieved for 88.5% of subjects receiving PPT vs 33.3% of subjects receiving SMC) (P < .001). PPT also produced larger adjusted mean differences, before vs after treatment, in numeric rating scales to assess quality of life: an increase of 1.8 points for parents (P = .047) and 2.0 points for children (P = .028). Results from the SDQ did not differ significantly between groups (P = .78). CONCLUSIONS: In a randomized controlled trial of children with FC, PPT was more effective than SMC on all outcomes measured, with the exception of findings from the SDQ. PPT should be considered as a treatment option for FC in children 5-16 years old. Dutch Clinical Trial Registration no: NL30551.068.09.