Background Research in the US and UK has demonstrated the effectiveness of person-centred planning (PCP) for people with intellectual disabilities. However, it is important to acknowledge problems that arise when implementing PCP. This paper considers barriers to PCP reported during a longitudinal study of the impact of PCP. Methods Person-centred planning was introduced over a 2-year period for 93 people of whom 65 had a plan developed. Information was collected regarding barriers to PCP every 3 months from key informants using self-completion questionnaires. Results Barriers to PCP were widespread particularly in relation to: availability of trained facilitators; availability of services; lack of time and reluctance of people other than paid support staff to engage in the PCP process. Conclusions Services need to be aware of potential barriers to PCP so that strategies can be developed to overcome them, the first of which should be the ongoing training and support of facilitators.