Introduction: Person-Centred Care (PCC) relies on effective communication and emphasises on co-operation in care between patients and healthcare professionals. WHO advocates this type of care as a key component of quality health care. Aim: To evaluate if person-centred nursing can improve treatment regimen adherence in patients with Myocardial Infarction (MI). Materials and Methods: During August-November 2016, 101 patients with MI, of age ≤85 years were randomly assigned to personcentred nursing group and usual care group and followed for two months. In the intervention group, a person-centred nursing process was added to care, emphasising the patient as a partner in care. Care was provided in co-operation with the patient, registered nurse and researcher. Data were collected using self-report adherence to the treatment regimen questionnaire and were analysed using SPSS software version 22 and chi-square test, independent samples t-test and paired t-test were applied wherever required. Results: Study results showed that the mean score of treatment regimen adherence did not have a significant difference before intervention, three weeks and two month after intervention in control group (p=0.692; p=0.581), but three weeks after intervention, the intervention group had a significant difference in the mean score of the treatment regimen adherence (p<0.001). Also, paired t-test results showed that two month after intervention the mean of adherence in person-centred nursing group was higher than control group (p<0.001). Conclusion: Person-centered nursing improved treatment regimen adherence in patients with MI. Further work is needed to examine whether this intervention can be sustained to improve clinical outcomes.