BACKGROUND: Studies from the amnesia literature suggest that errorless learning can produce superior results to errorful learning. However, it was found in a previous investigation by the present authors that errorless and errorful therapy produced equivalent results for patients with aphasic word-finding difficulties. A study in the academic literature of phoneme discrimination learning found that errorful learning produced equivalent results to errorless learning when feedback was given. In the authors' previous study, feedback was available to the participants in the errorful therapy. It is possible, therefore, that this feedback may have improved the results from errorless learning - thereby reducing an underlying difference between the two techniques. Generally, feedback is thought to aid learning, however, there is little information in the speech therapy literature about this factor. AIMS: The present investigation was conducted as a follow-up to authors' original study to compare errorless and errorful therapy for the amelioration of aphasic word-finding difficulties. The second aim was to replicate key findings from the original study: namely, that recognition memory, executive/problem-solving skills and monitoring ability predict immediate and long-term naming improvements but not the participants' remaining language ability. METHODS AND P[ROCEDURES: Seven of the original 11 participants took part in a multiple baseline, crossover, case series design. OUTCOMES AND RESULTS: The previous results were replicated: errorless and errorful therapy produced equivalent results immediately post-therapy and at follow-up. There was no effect of omitting feedback - the participants learnt equally well without therapist's feedback about whether or not their response was correct. In addition, executive/problem-solving skills and monitoring ability again predicted immediate naming improvements not language ability. CONCLUSIONS: The findings support the view that cognitive abilities and in particular executive function are important contributors to rehabilitation.