This research describes the impact of Agenesis of the Corpus Callosum (AgCC) on working memory and general neurobehavioural functioning, and its impact on the functional brain organisation of working memory processes using a specially designed fMRI Brown-Peterson task. A cohort of 28 children with AgCC and 16 healthy children completed neurobehavioural testing and an MRI. This is the first comprehensive report of neurobehavioural consequences of AgCC in children and provides insight into their functional brain networks underlying higher cognitive functions.