Dyslexia is a condition characterized by difficulty of reading given adequate intelligence and educational opportunities, primarily associated with a phonological processing deficit. In this study we show that dyslexic children also show a deficit in working memory compared to a control group, measured with fMRI. A working memory n-back task with three load levels was used. Behavioral data showed that the dyslexics had poorer performance compared to the controls. fMRI data showed that the dyslexics had reduced activation in the prefrontal and parietal cortices and the cerebellum compared with the controls. These results imply a working memory deficit in dyslexia.