Several studies have shown that transcranial direct current stimulation (tDCS) is able to enhance performances on verbal and visual working memory (WM) tasks. Available evidence points to the right dorsolateral prefrontal cortex (DLPFC) as a critical area in visual WM, but to date direct comparisons of the effects obtained by stimulating the left versus the right DLPFC in the same subject are lacking. Our aim was to determine whether tDCS over the right DLPFC can differently affect performance as compared with left DLPFC stimulation. Ten healthy subjects performed a memory-guided visuospatial task in three conditions: baseline, during anodal stimulation applied over the right and during anodal stimulation applied over the left DLPFC. All the subjects also underwent a sham stimulation as control. Our results show that only active stimulation over the right DLPFC is able to increase performance when compared to the other conditions. Our findings confirm the crucial role played by the right DLPFC in spatial WM tasks.