The aim of this study was to evaluate the effectiveness of a computer-based executive function (EF) training in children with specific language impairment (SLI). Ten children with SLI, ages 8 to 12 years, completed a 25-session training of visuospatial working memory, inhibition and cognitive flexibility over a 6-week period. Treatment outcome was examined directly after training and at 6 months follow-up by tasks of the three trained EF, tasks of untrained neurocognitive functions (verbal working memory, attention, planning and fluency), and ratings of EF and behavioral problems by parents and teachers. Directly after training, results showed significant improvement on cognitive flexibility and a positive trend for visuospatial storage and inhibition. At 6 months follow-up, the children performed significantly better on tasks of all three trained EFs. Furthermore, the results showed significant improvement on sustained attention, attention control, parent- and teacher-rated attention behavior and parent-rated EF and externalizing behavior with medium effect sizes. The results of this pilot study highlight the importance of a large-scale, randomized controlled trial examining the possible effects of EF training in children with SLI.