Results: Low adherence was related to AED beliefs (doubts about necessity: t(577) = 3.90, p < 0.001) and concerns: t(995) = 3.45, p = 0.001), reported limitations in capability and resources (t(589) = 7.78, p < 0.001) and to perceptions of a lack of involvement in treatment decisions (t(623) = 4.48, p < 0.001). In multiple logistic regression analyses, these factors significantly (p < 0.001) increased variance in reported adherence, above that which could be explained by age and clinical variables (seizure frequency, type, epilepsy duration, number of AEDs prescribed).Significance: Variables identified in the NICE Medicines Adherence Guidelines as potentially important factors for adherence were found to be related to adherence to AEDs. These factors are potentially modifiable. Interventions to support optimal adherence to AEDs should be tailored to address doubts about AED necessity and concerns about harm, and to overcome practical difficulties, while engaging patients in treatment decisions