Use of computers by children has increased rapidly, however few studies have addressed factors which may reduce musculoskeletal stress during computer use by children. This study quantified the postural and muscle activity effects of providing forearm support when children used computers. Twelve male and 12 female children (10-12 years) who regularly used computers were recruited. Activities were completed using a computer with two workstation configurations, one of which provided for forearm support on the desk surface. 3D posture was analysed using an infra-red motion analysis system. Surface EMG was collected from five muscle groups in the neck/shoulder region and right upper limb. Providing a support surface resulted in more elevated and flexed upper limbs. The use of forearm or wrist support was associated with reduced muscle activity for most muscle groups. Muscle activity reductions with support were of sufficient magnitude to be clinically meaningful. The provision of a supporting surface for the arm is therefore likely to be useful for reducing musculoskeletal stresses associated with computing tasks for children.