Objective: This is a randomized control trial examining the efficiency of computerized cognitive training (CCT) for adults with ADHD, comparing two training conditions with graded levels of executive cognitive demands. Method: Adults with ADHD (n = 60) were randomized into study (n = 34) and control (n = 26) groups. Training was conducted with the computerized AttenFocus program. Control group received a simple, non-hierarchical version with less executive demands. Results: Significant positive changes in symptoms ratings, ecological measures of executive functions, and occupational performance were found in both groups. No significant changes were found in variables of neurocognitive performance battery and quality of life. No significant time by group interaction effects were found. Conclusion: No benefits of the intervention were found relative to the control. Lack of interaction effects may be due to insufficient power, non-specific cognitive training or placebo effects. Results demonstrate some positive findings for general CCT, yet do not support the inclusion of specific higher level executive training.