mg warfarin initiating dose appeared to be safe in adult Thai patients. However, the efficacy of 3-mg starting dose as determined by the proportion of patients who achieved the target INR between day 3 and day 5 of warfarin treatment was relatively less efficient when compared with that previously reported with a 5-mg loading dose. Further randomized,prospective study is required to examine the efficacy of 3-mg versus higher warfarin starting dose in Thai patient