Introduction: Cerebral palsy is an unprogressive chronic encephalopathy that leads to neurological disorders and is the most common childhood motor disability. Children with cerebral palsy suffer from impaired muscle function, such as spasticity, muscle weakness and loss in voluntary motor control which affects activity and social participation. Studies use various types and combinations of strength training, one of which is progressive resistance exercise. Purpose: The purpose of this study is to determine the effect of resistance training on muscle performance and functional activities of children with cerebral palsy. Methods: A systematic review of randomized controlled trials was conducted in databases Cinahl, Medline and PEDro. Results: According to exclusion criteria seven randomized controlled studies were included in the analysis. Five studies used progressive resistance exercise, while two studies used a combination of resistance exercise and aerobic exercise of stationary cycling. Six studies reported significant improvement in muscle strength between groups, two studies reported significant improvement in parameters of walking. Studies did not report any significant effects on mobility, gross motor function or endurance between groups. All studies compared the effects of exercise to a control group, which continued with their usual physiotherapy during the time of study. Discussion and conclusion: Evidence suggest resistance training is an effective method of muscle strengthening in children with cerebral palsy, but it is not so effective when improving other functional abilities which are important for participants. To improve complex functional abilities the exercise plan should be more task oriented and reach more components that are often impaired in individuals with cerebral palsy. To reach more substantial conclusions further studies that would evaluate long-term effects are needed. While participating in the programme, no adverse effects like spasticity or impaired flexibility were reported.