Objective To investigate the situation of visual memory impairment in patients with myasthenia gravis (MG).Methods Thirty MG patients and 28 normal control subjects were tested with a battery of computerized tests (modified Smith working memory software), which was designed to assess visual-spatial and visual-object working memory.Results There was no significant difference in the accuracy rate of visual-object working memory test between the MG group and normal controls (MG group 73.4% ±9.7%, normal controls 72.7% ±8.5%).The accuracy rate of the visual-spatial working memory test in the MG group (76.6% ± 16.5%) was significantly lower than that in the normal controls (86.6% ±7.5%, Z = -2.204, P = 0.028).Conclusion The visual-spatial working memory is probably impaired while the visual-object working memory is relatively spared in MG patients.