Objective: Medication adherence rates after coronary artery bypass graft (CABG) surgery are low due to intentional (e.g., deliberately choosing not to take medication) and unintentional (e.g., forgetting to take the medication) person-related factors. There is a lack of studies examining the psychological factors related to non-adherence in CABG patients. Intentions to take medication and planning when, where, and how to take medication and to overcome unintentional forgetting to take medication were hypothesized to be independently related to medication adherence. Furthermore, planning to overcome forgetting was hypothesized to be more strongly associated with medication adherence in patients who have stronger intentions to take medication, reflecting the idea that planning is a factor that specifically helps in patients who are willing to take medication, but fail to do so.Methods: Measures of medication adherence, intention and planning were collected in a sample of (N = 197) post-CABG surgery patients followed from discharge (baseline; Time 1) over a 12-month period (Time 2) in Boo-Ali Hospital in Qazvin, Iran. A series of hierarchical multiple regression analyses were performed in which medication adherence at Time 2 was regressed onto socio-demographic and clinical factors, the hypothesized psychological variables (adherence-related intention and planning), and interaction terms.Results: Intentions to take medication (B = .30, P < .01), action planning when, where, and how to take the medication (B = .19, P < .01), and coping planning how to avoid forgetting to take the medication (B = .16, P < .01) were independently related to medication adherence. Beyond that, action planning x intention to take medication (B = .06, P < .05) and coping planning x intention (B = .07, P < .01) interaction also significantly predicted adherence.Conclusion: Intention to take medication was associated with better medication adherence and action and coping planning strategies to avoid forgetting to take the medication added significantly to the prediction of adherence in the year following CABG discharge. This is in line with theory and evidence about the independent roles of intentional and unintentional predictors of non-adherence. As hypothesized, planning to overcome unintentional forgetting to take the medication was more predictive of medication adherence in those patients who reported higher intentions to take medication, reflecting the idea that planning helps patients overcome unintentional reasons of being non-adherent. (C) 2014 Elsevier Inc. All rights reserved.