Our purpose was to compare the effect of three different conventional anti–ischemic therapies and of intracoronary glyceryl trinitrate (GTN) on coronary flow and the clinical outcome in two types of patients with non–obstructive coronary disease (NCAD) – patients with slow coronary flow phenomenon (SCFP) and those with slow flow associated with left ventricular hypertrophy (LVH) secondary to hypertension (SCFLVH). Study design – a retrospective single–center cohort study. The coronary flow was assessed using the corrected thrombolysis in myocardial infarction (TIMI) frame count method (cTFC) in 87 consecutive patients, with cTFC >25 frames and unstable angina treated with β–blocker (BB), with BB and oral nitrate (BB+N) and with β–blocker (BB), calcium channel blocker (CCB), with or without oral nitrate, BB+CCB±N before and after the intracoronary injection of glyceryl trinitrate, GTN (200 µg). Compared with SCFP, the intracoronary nitrate administration improved the coronary flow as tendency in the subgroup with SCFLVH (cTFCn – 33.9±10 frames vs 39.7±14.8 frames, p= 0.091). This response was most pronounced in patients with SCFLVH receiving combined therapy with BB+CCB±N (SCFLVH vs. SCFP – cTFCn 29.2±4.6 frames vs. 41.6±12.1 frames, p–NS). In the group with SCFP, an insignificantly higher incidence of ischemic–driven hospital readmissions was observed during follow–up. In the whole study population, the period free of adverse events was least in duration in the patients that recieved BB+N, intermediate with the intake of BB alone and longest in the patients treated with BB+CCB±N (38.6±10.3 days vs. 51.7±6.5 days vs. 73±6 days, p–NS). In conclusion, in the absence of obstructive coronary disease, partial reversibility of the increased coronary vascular resistance after intracoronary GTN is observed only with CCB therapy in patients with slow flow secondary to hypertensive disease, but not in SCFP.