background: non-adherence to treatment is an important and often unrecognized risk factor that contributes to reduced control of blood pressure (bp). objective: to determine the association between treatment adherence measured by a validated version in portuguese of the 8-item morisky medication adherence scale (mmas-8) and bp control in hypertensive outpatients. methods: a cross-sectional study was carried out with hypertensive patients older than 18 years, treated at six of the family health strategy units in maceió (al), through interviews and home blood pressure measurements, between january and april 2011. adherence was determined by mmas-8 version translated for this study. the patients were considered adherent when they had a score equal to 8 at the mmas-8. results: the prevalence of adherence among the 223 patients studied was 19.7%, while 34% had controlled bp (> 140/90 mmhg). the average adherence value according to the mmas-8 was 5.8 (± 1.8). adherent patients showed to be more prone (or = 6.1, ci [95%] = 3.0 to 12.0) to have blood pressure control than those who reached mean (6 to <8) or low values (<6) at the adherence score. the portuguese version of mmas-8 was showed a significant association with bp control (p = 0.000). conclusion: the diagnosis of non-adherent behavior through the application of mmas-8 in patients using of antihypertensive medications was predictive of elevated systolic and diastolic bp.