BACKGROUND: The importance of adequate management and control of high blood pressure (HBP). OBJECTIVE: To estimate the prevalence of hypertension control and therapeutic inertia among adults treated at primary health care units (PHCU) in the city of Joinville, as well as the associated factors. METHODS: A cross-sectional study, which included cluster sampling and analysis of medical records, with the evaluation of 415 patients with high blood pressure. We evaluated the blood pressure (BP), increments of therapy, risk factors and comorbidities. RESULTS: There was prevalence of females and nursing appointments. The age ranged between 28 and 90 years (mean of 61.5 years). There was a reduction in the mean BP (155.8 ± 20.8/95.7 ± 10.6 mmHg to 140.3 ± 22/84.1 ± 12.4 mmHg) between the first and last record and the final normal BP in 36.6% of patients, with similar results for men and women. Over the past 12 months, the BP was high on 1,295 occasions, and there was a therapeutic increment on only 156 occasions (12.0%). 1.85 drugs were used per patient, mainly diuretics and ACE inhibitors. There was high prevalence of obesity (40%), diabetes (41%), high LDL (46%) and left ventricular hypertrophy (25.5%). CONCLUSION: The high therapeutic inertia, low control of high blood pressure and the large number of comorbidities suggest the need for continuing education programs for health professionals and other measures to improve the disease control in primary health care units.