The aim of this study was to investigate reliability of Myotonometer measurements, by assessing muscle tone in muscle rectus femoris in children with cerebral palsy and children without disabilities. Differences in muscle tone between groups and conditions, contracted or relaxed, were also investigated. A total of 15 children with cerebral palsy and 15 children without disabilities participated. Intrarater reliability of Myotonometer measurements showed high to very high intraclass correlation, under both conditions and in both groups. Interrater reliability showed high to very high intraclass correlation under both conditions in the control group and in the cerebral palsy group under contracted condition and moderate under relaxed condition. There were slight differences in tissue displacement between groups, although not statistically significant. Myotonometer measurements are reliable when assessing muscle tone in children. However, there is still a need to investigate this method for objectively quantifying increased muscle tone in children with cerebral palsy.