Objectives To investigate myocardial relaxation times and perfusion values in spontaneously hypertensive rats (SHRs) at various stages of the disease, with or without anti-fibrotic therapy, and to correlate magnetic resonance imaging (MRI) findings with histopathological myocardial fibrosis and capillary density. Methods Five groups of rats underwent MRI at 4.7 T. They were either untreated or treated with an aldosterone-synthase inhibitor. T1, T2 and T2* relaxation times were determined and myocardial perfusion was quantified from an arterial spin labelling sequence. MR relaxation times and perfusion values were compared with the fibrotic content and capillary density of the myocardium obtained at histology after euthanasia.