Background: Reproduction conduction aphasia is a disorder of phonological production characterised by phonological errors occurring particularly with longer words in all tasks requiring spoken output. There have been few previous studies of therapy for subjects with this disorder. Aims: The study investigates the effects of a treatment procedure involving the detection and correction of the errors in speech production with a single subject, MB. We also seek to establish the nature of MB's underlying deficit, and show how it changes as a result of treatment. Methods & procedures: Treatment effects were investigated in a single case study using multiple baselines over tasks, materials, and time. An in-depth cognitive neuropsychological case study was used to investigate the nature of MB's speech production deficit. Outcomes & results: MB had impaired naming, repetition, and oral reading particularly with longer words, but good word comprehension. Her errors were primarily phonological, with many repeated attempts ("conduite d'approche"). Production of non-words was less accurate than real words. The treatment improved production in all modalities and across a variety of tasks (including non-word reading). Further analysis of assessment results suggested that MB's impairment was at the level of phonological encoding and that therapy had improved phoneme production across all word positions. Conclusions: Treatment was successful and generalised across items and to connected speech. MB's deficit could be characterised as a difficulty in the process of phoneme retrieval, and this improved as a result of the treatment.