Objective: This study aimed to explore the applicability of temporal self-regulation theory (TST) in adherence to medication, using two self-report measures of behaviour. Design: Recruited through TurkPrime, 191 US adults completed a two-part study. Main outcome measures: TST constructs of intention, behavioural prepotency (past behaviour, habit, cues), self-regulation (self-control, planning) with regimen complexity, and side effects were measured at time one. At time two, adherence behaviour over the previous week was measured using a revised medication adherence rating scale and an adapted timeline follow-back. Results: Constructs of TST accounted for 51.5% of variance in adherence as assessed by the rating scale. Past behaviour and cues were significant. Habit and planning moderated the intention-adherence relationship. Similarly, the TST constructs accounted for 20.6% of variance when measured by the timeline follow-back. Intention, cues and self-control were significant predictors. Interestingly, cues was the only common significant predictor. Conclusion: TST was partially supported and the role of both rational and automatic factors was supported, however findings differed depending on the type of measure. Future developers of interventions may consider targeting cues to improve medication adherence. Future research also needs to further explore the role of intention, past behaviour, self-control, habit and planning in medication adherence.