The purpose of this study was to establish an influence on static and dynamic postural control in sitting for voluntary arm movement for children with diplegic cerebral palsy. The investigation was fulfilled with control and experimental groups. The control group included ten healthy children and the experimental group included ten children with cerebral palsy. The age of the children was from 10 to 13 years. Subjects had to perform the same task with a single arm for four times. Every time the demands of postural control were increasing – the distance between objects and outward stability was changing. Task performing time was measured and visual estimation of the quality of postural control was done. The study showed that children with cerebral palsy performed the task slower than healthy ones (P < 0.05). The task performance time in the experimental group increased depending on growing distance between objects (p <0.05) and increased depending on decreasing outward stability (p < 0.05). The task’s time in the control group increased only when the distance was increasing between objects (p < 0.05), though when outward stability was decreasing the task’s performance time decreased (p < 0.05). A connection between task’s performance speed in standard conditions and task’s performance speed when the distance between objects was increased (r = 0.8), outward stability was decreased (r = 0.79), the distance between objects was increased and outward stability was decreased (r = 0... [to full text]