In the United States 13% to 9% of children (ages 0–17 years) have special healthcare needs (1). Unfortunately, 50–55% of children and their families do not follow treatment plans as prescribed (2). Such high rates of nonadherence (i.e., extent to which a person’s behavior does not correspond with agreed upon recommendations from a healthcare provider (3)) have significant negative consequences, including: greater risk of relapse, increased morbidity and mortality, unnecessary changes to the regimen, development of drug resistance, decreased cost-effectiveness of medical care, and inaccurate clinical trial results (2, 4–7). Thus, documentation of nonadherence rates, identification of barriers to or strategies to improve adherence, and development and integration of adherence interventions are imperative. Regrettably, despite increased recognition that adherence is a significant issue across pediatric disease groups, there remains a lack of consensus regarding the “best” adherence measure. Patient, parent, and provider-report, pharmacy refill data, pill counts, serum assays, and electronic monitors have all been used to monitor medication adherence with varying success. Of note, even though there remains no clear “gold standard” measure of medication adherence (8), the use of electronic monitoring has increased and is often employed as the standard to which other measures of adherence are compared (e.g., (9–11)). Given increased recognition of the role of adherence in health outcomes, the use of electronic monitors to assess adherence, and the increasing use of electronic measures as key components in interventions to improve adherence, it is critical that objective evaluation of their utility and evidence of their functional capabilities in real world settings be made available. In order to aid decision making related to using electronic adherence monitors in future studies or incorporating such measures into clinical practice in order to improve adherence rates, this systematic review will 1) provide a brief description of currently available electronic measures of medication adherence, 2) discuss the strengths and weaknesses of these measures (and validation information when available), and 3) provide examples of their use and relevant empirical data for a subsample of measures from our own research. A systematic review was completed using PubMed (12) to identify previous studies that used electronic measures of medication adherence in pediatric populations through February 2010. Search terms included: (adherence OR compliance) AND (electronic, technology, MEMS, Doser, MDIlog, Smartinhaler, Medsignals, Pillphone, Nebulizer, Chronolog, Drug Exposure Monitor). Initial device names were included from the authors’ experiences; additional names were added as identified through other search terms. References of identified articles were examined to identify additional published studies. Final inclusion/exclusion criteria and article selection is further illustrated in the Figure. A summary of monitor use by disease group is provided in the Table. Figure Study selection flow diagram (60). Reasons for exclusion: (1) not written in English; (2) primary or original study data not included; (3) electronic monitor of oral medication adherence not included (not prescribed treatment regiment [eg, blood glucose ... Table 1 Electronic monitor by illness group and websites for additional product and pricing information