Objectives: To identify an empirical method for identifying patients with ‘high expectations’ of orthodontic treatment with fixed appliances using a questionnaire-based approach. Design: Secondary analysis of data from four studies which collected data on patients’ expectations of orthodontic treatment using the same questionnaire. Setting: Secondary care orthodontic services. Participants: All four datasets comprised new patients aged 12–15 years, with no history of orthodontic treatment, who fulfilled the criteria for NHS treatment using the Index of Orthodontic Treatment Need (IOTN). Unpublished dataset 1 comprised 100 participants, while dataset 2 had 70 participants, dataset 3 had 67 participants and dataset 4 comprised 40 participants. Methods: The questionnaire utilised in all studies had a question which asked respondents to rate seven different expectations of outcome relating to straight teeth, better smile, ease of eating, speaking, cleaning teeth, improved career prospects and social confidence. Dataset 1 was analysed to determine the proportion of patients who had rated all seven outcome expectation items at a maximum score. Similar analyses were performed for the other three datasets to explore the trend in the proportion of patients with high expectations over time. Results: For dataset 1, 2.0% of participants had high expectations, as defined by their scores on the questionnaire. The proportions for the datasets 2, 3 and 4 were 4.0%, 4.5% and 2.5%, respectively. Conclusion: The method outlined provides an empirical basis for identifying patients with statistically infrequent high expectations. This can potentially help clinicians in the management of such patients.