Background: The cornerstone of anticoagulant therapy is warfarin, although using it has been linked to a number of problems, most notably bleeding. Patients who are adequately informed about warfarin can reduce adverse medication responses and other related consequences while also improving anticoagulation control. The study's goal was to evaluate how patients' understanding of warfarin was impacted by their counselling from chemists. Techniques: A prospective randomised controlled trial was conducted at the National Heart Centre of Shahid Gangalal, Kathmandu, Nepal. Enrolling the individuals in the intervention and control groups was done using a straightforward random sample procedure. The study involved 99 patients in all. To determine each group's baseline knowledge, the same questionnaire was given to them both. The intervention group received verbal counselling for twenty minutes, while the control group did not get any chemist intervention. After two months, a final evaluation of both groups' knowledge levels was conducted using the same questionnaire. Findings: Following the intervention, there was a statistically significant increase (p<0.05) in the proportion of patients in the counselled group who knew enough about warfarin. The findings also revealed that, following the intervention, a notably higher percentage of patients in the intervention group had improved INR (International Normalised Ratio) control. There was no discernible correlation between the patients' knowledge score, age, gender, or length of therapy. Conclusion: Patients' understanding of warfarin can be greatly enhanced by counselling from chemists. Key words: Warfarin, INR, counselling, anticoagulation, and knowledge.