The Gap Theory of Parasuraman et al. (1985) defines service quality as 'a function of the gaps between the service expectations of consumers (patients) and their service perceptions'. Since reducing these gaps must comprise the principal targets of any form of strategic marketing, this pilot study was therefore undertaken to develop customized SERVQUAL instrument to quantify patients' expectations and perceptions of orthodontic dental service quality. The feedback and modifications to the delivery of orthodontic service delivery provided by such an instrument will render a means by which orthodontists can monitor and improve their services. The satisfaction created from these improvements is of paramount importance and is related to one of the primary characteristics of the profession of orthodontics--to serve. Over a 12-week period, patients receiving orthodontic treatment from a University graduate clinic and a private practice clinic completed a customized SERVQUAL questionnaire consisting of 19 paired expectation/perception statements scored via a ten-point Likert-type scale. Statistical e aluations of the derived scores not only provided valid and reliable assessments of orthodontic service quality viewed from the perspective of patients, but also information to facilitate strategic development for continuous improvement. (Abstract shortened by UMI.)