Purpose: There is a lack of research covering the training requirements of organisations implementing highly demanding information systems (HDISs). The aim of this paper is to help in the understanding of appropriate training requirements for such systems. Design/methodology/approach: This research investigates the training delivery within a customer-facing organisation that successfully implemented an HDIS. A case study was undertaken to identify resource allocation during the implementation lifecycle and training guidelines were prepared following in-depth interviews with client and supplier consultant practitioners. Findings: Organisations implementing HDISs should invest in training throughout the implementation lifecycle. Two areas of training were found to be of importance: end-user training to avoid technical-isomorphism and post-implementation training to avoid system atrophy. Practical implications: Literature shows that training attracts the smallest proportion of the implementation resources. This research shows, however, the critical role training plays in delivering a successful HDIS implementation. Originality/value: The phasing of training requirements allows training resources to be allocated more effectively into end-user and post-implementation training, which is necessary for the full benefits of HDIS to be realised. (Contains 2 figures.)