In a prospective cohort study the influence of self-monitoring of the Inter
national Normalized Ratio (INR) was examined on 100 consecutive patients fo
r a period of 6 months. Quality of life changed in a positive way. Independ
ence and better organization of vacation and spare time were the most frequ
ently mentioned advantages of the new method. Quality of anticoagulation by
using a self-monitoring device was improved compared to the values before
using the self-monitoring device. For measuring the INR, the usage of a por
table monitor as the primary method can be recommended in selected patients
receiving oral long-term anticoagulation.