Abstract: This study examined the cognition and motor skills in a 14-year-old boy with severe writing difficulties. This case, zl wrote very slowly, his handwriting was bad and hard to be recognized. The study showed that his intelligence, reading comprehension and listening comprehension were normal. There were no differences between zl’s performance on accuracy of naming single characters, two-character words, numbers, and objects with that of same-aged controls. But his speed was significantly slower than that of the controls. This study focused on zl’s fine motor, visual-spatial, visual, and sequential processing skills. The results showed that his visual memory and motion detection was normal. His motor skill, visual-spatial, and sequential processing abilities were significantly worse than those of the controls. Neurophysiology examination found that his brain wave was abnormal, MRI scans indicated that myelinated corpus callosum and cerebellum developed abnormally. These findings suggested that zl’s writing difficulties reflected his general motor coordination disorders, and had neurophysiologic foundations. The implications for cognitive neurology mechanism and early diagnosis of writing difficulties were discussed

Key words: developmental coordination disorder, writing difficulties, case study, visual-spatial processing, fine motor skills