Abstract To assess the effect of brain damage and Borderline IQ on motor performance in five-to eight-year-old children, a sample of 39 brain-damaged subjects was compared with 38 control subjects on a test of speed of motor performance that had been standardized on a group of normal children. The groups were matched for IQ, age, and sex. Brain-damaged subjects were found to be slower than control subjects with each hand, and particularly with the non-preferred hand. Quite similar findings occurred when the children with IQs in the 71–90 range were contrasted with children with IQs in the 91–110 range. No significant interactions between brain-damage and level of intelligence were found. Thus, both brain damage and Borderline intelligence related independently to diminished motor efficiency. The task of differentiating diagnostically between these two effects awaits future study.