The article describes a clinical case of BRAHH syndrome in a patient with arterial hypertension and permanent atrial fibrillation (AF). The patient took perindopril 10 mg, indapamide 2.5 mg, amlodipine 10 mg, bisoprolol 2.5-5 mg daily. She was admitted to a hospital complaining of severe weakness, a heart rate decreases to 38 beats per minute against the background of high blood pressure. During the examination, she was diagnosed with complete atrioventricular block against the background of AF, stage 4 chronic kidney disease and severe hyperkalemia (potassium 8.7 mmol/l). The patient was prescribed treatment aimed at eliminating hyperkalemia, and temporary pacing was established. Against this background, her condition improved, and the complete atrioventricular blockade was resolved. This clinical example meets the criteria of BRAHH syndrome, since against the background of taking an atrioventricular node blocker in a small dose, a patient with chronic kidney disease and severe hyperkalemia developed complete atrioventricular block against the background of AF, accompanied by high blood pressure.