There are several modalities to monitor oral anticoagulant therapy, namely: monitoring by a secondary care specialist in the hospital setting; monitoring by the general practitioner/ family doctor in the primary care setting; monitoring by private laboratories of clinical analysis; self-monitoring with point-of-care devices. In Portugal, the most frequent modality is still the hospital monitoring/anticoagulation clinics, although monitoring in the primary care/routine medical care setting has began to be implemented in some areas of the country since five years ago. Anticoagulation clinics are still actually the organizations that optimize better the clinical and laboratorial follow up of the patients anticoagulated with warfarin. In 2011, anticoagulation control quality was evaluated, in the setting of an anticoagulation clinic (Santo António Hospital, Porto Hospital Center) by determining the proportion of INRs within the therapeutic range. The evaluation focused ambulatory patients, during a period of two months, corresponding to 1067 controls from 687 patients (mean age: 69±13 years; 54%, n=567, female gender). 71% of controls (n=756) were within the therapeutic range. 27% of controls were outside the therapeutic range, after exclusion of patients with programmed surgery or invasive proceedings. 13.8% of controls were below the therapeutic range and 8.6% (n=92) of the latter had INR ≤ 1.5. Above therapeutic range were 13.2% (n=139), from which 4.4% (n=46) had an INR between 5-8 and 0.3% (n=4) an INR ≥ 8. The group of primary care Health Centers (Portuguese acronym ACES) of the Baixo Tâmega region conducted, also in 2011, an evaluation of the anticoagulant control quality, by determining the proportion of INRs within the therapeutic range. The results were similar to those found in the anticoagulation clinic of the Hospital de Santo António which shows that the quality of monitoring in the primary care setting can have the same quality of the anticoagulation clinics monitoring. The introduction of the new oral anticoagulants, that don't require laboratorial monitoring constitutes a challenge. In Portugal, there is no experience yet to respond to the question if, in this new context, the anticoagulation clinics will be fundamental for the registration of patients, the evaluation of the hemorrhagic risk, the clinical follow up or the evaluation of the adherence to therapy.