ABSTRACT Background: Since 2003, it has been routine practice at Children’s and Women’s Health Centre of British Columbia to monitor serum levels of prolactin in pediatric patients with cystic fibrosis who are receiving domperidone. Although a pharmacologic relationship between domperidone and prolactin has been documented in the literature, there is no information about routine monitoring of prolactin, and guidance on interpretation of prolactin values is lacking.Objectives: To characterize how prolactin levels were being used in monitoring patients with cystic fibrosis who were receiving domperidone therapy at this institution, to evaluate the need for this practice, and to formulate recommendations accordingly.Methods: A chart review was conducted for pediatric patients with cystic fibrosis who had been receiving domperidone therapy and whose serum prolactin levels had been monitored between June 1, 2001, and October 1, 2005.Results: A total of 219 samples had been drawn, from 49 patients, for determination of prolactin level. Of these, 100 (45.7%) were above the normal range. Of the values above the normal range, 86 (86%) led to no dosage adjustment of domperidone and 14 (14%) led to either a decrease in dose or discontinuation of therapy. None of the elevated prolactin levels were associated with supratherapeutic doses of domperidone.Conclusion: The role of routine monitoring of prolactin in this patient population requires further study. In particular, more information is needed about prolactin levels in pediatric patients and the relationship of prolactin level to domperidone dose.