Background: Warfarin has long been established as the oral anticoagulant of choice. The benefits of warfarin depend on maintaining the International Normalized Ratio (INR). It has been shown that the optimal INR target range is 2-3 for AF patients. Very less number of patients had been reported to achieve and remain in that target INR range. The prevalence of AF in the general population is about 1.6% in women and 2.4% in men and is generally lower in Asian countries

Aim: To determine the frequency of achieving target INR in patient on warfarin for atrial fibrillation.

Methodology: This is cross sectional study conducted at national institute of cardio vascular disease, Karachi from 31^st May 2016 30^th November 2016.The sample size of the study were 111, and nonprobability convenience sampling technique was used.

Results: Among study population 61 (54.9%) were male and 50(45%) female patients. Mean duration of atrial fibrillation was 3.44±0.97 years. The mean duration of warfarin taken was 11.34±3.96 months. INR (2-3) target achieved in 72(64.9%) patients. Significant association of achieved INR target was observed with duration of atrial fibrillation, duration of warfarin, hypertension, stroke, and Left ventricular dysfunction. 

Conclusion: Target of INR was achieved in 64.9% patients when these patients were given warfarin doses of 5.0 to 7.5 mg/day.

Keywords: Achieving Target INR, Warfarin, Atrial Fibrillation.