Evidence on the effect of systemic exercise programs to improve the standing balance with the Nintendo Wii system is very limited and its post-treatment effectiveness is unknown in cerebral palsy (CP) patients.Primary aim was to compare the effect of Nintendo Wii balance board (Wii-therapy) and standard physiotherapy (SPT), on the performance of standing balance in children and adolescents with CP. Secondary aim was to determine the post-treatment effectiveness of Wii-therapy and SPT.Two-arm, matched-pairs, parallel-groups, randomized, controlled clinical trial.Outpatient Rehabilitation Centre in the city of Talca.Patients with CP type spastic hemiplegia (SHE) and spastic diplegia (SDI), aged 7 to 14 years, and level I or II of GMFCS or GMFCS-ER. Were excluded patients with FSIQ<80, epilepsy, previous surgeries and application of Botulinum Toxin-A in the lower limb, uncorrected vision and hearing disorders.Thirty-two CP patients (10.7±3.2 years old) were randomly assigned to either Wii-therapy (SDI=7; SHE=9) or SPT intervention (SDI=7; SHE=9). In each group, patients received three sessions per week over a period of 6 weeks. Standing balance was assessed at baseline and every 2 weeks. Additionally, two follow-up assessments (4 additional weeks) were performed to determine post-treatment effectiveness. Standing balance was quantified on force platform obtaining the outcomes area of center-of-pressure (CoP) sway (CoPSway), standard deviation in the medial-lateral (SDML) and the anterior-posterior (SDAP) directions, and velocity in both directions (VML and VAP).Compared to SPT, Wii-therapy significantly reduced the CoPSway (P=0.02) and SDAP in the eyes-open condition (P=0.01). However, the effects wane after 2-4 weeks. Post-hoc analysis revealed that only SHE children benefited from Wii-therapy.Wii-therapy was better than SPT in improving standing balance in patients with CP, but improves the balance only in SHE patients. Also, Wii-therapy effectiveness waned 2-4 weeks after the end the intervention.A systematic exercise program like Wii-therapy using the Nintendo Wii Balance Board device can be considered to improves the standing balance in patients with CP, specifically in the SHE type. This program is easy to transfer to physiotherapists and rehabilitation centers.