Oral acenocoumarol therapy is a most commonly practised drug for the follow up management of the patients of deep vein thrombosis. In-spite of achieving target INR values, we still find varying grades of post thrombotic syndrome on follow up. The correlation of target INR and Villalta score was studied to express the gravity of post thrombotic syndrome.The retrospective observational study was conducted from case records of 100 DVT patients on acenocoumarol after fulfilling the inclusion criteria. The series of INR test done for these patients during 6 months of follow up were recorded. Post thrombotic syndrome, known sequelae of DVT, was assessed by Villalta score and correlated with the target INR. The average INR test done during six months was 21.52±4.98. The therapeutic INR was seen in 60.95%, subtherapeutic INR in 26.34% and supratherapeutic INR in 12.83% patients (p<0.05). The patients who were having INR within normal range in more than 50% of tests conducted during 6 month (n=68) were having mean Villalta score of 4.44±3.52 contributing to 4.41% of cases with grade 3 PTS. In contrast, in patients with INR within the normal range in less than 50% test performed, the mean Villalta score was 10.06±5.81 amounting to 37.5% of cases with grade 3 PTS (p=0.0009). A moderate correlation was observed between percentage of INR test within normal range and Villalta score (r=-0.50, p=0.001) and PTS grading (r=-0.51, p=0.0001). The patients who achieved therapeutic INR with acenocaumarol had better outcome (lower villalta scoring and recanalization) than the patients who had sub therapeutic INR.