The aim of the study was to evaluate the geometry and structure of coronary artery (RS) of spontaneously hypertensive rats (SHR) and Wistar rats during ontogeny. We used SHR and Wistar rats of the age: 3 weeks (3w), 9 weeks (9w), 17 weeks (17w), and 52 weeks (52w). Blood pressure (BP) was measured by plethysmographic methods on the tail artery. The animals were perfused with a glutaraldehyde fixative (90 mmHg - 3w, 120 mmHg - 9w, 17w, 52w). RS was processed for electron microscopy. Wall thickness (WT) and cross sectional area (CSA) were evaluated in light microscopy. Volume densities (VD) of smooth muscle cells (SMC) and extracellular matrix (ECM) were determined in electron microscopy. No difference in BP between 3w SHR and controls was observed. The difference in this respect was found between age-matched groups in later period in SHR. Cardiac hypertrophy was found in all SHR groups. In 3w old SHR WT and CSA did not differ in comparison to the controls, both were increased from the age of 9w. VD of SMC compared to Wistar rats was increased in 9w and 17w, it was decreased in 52w; VD of ECM was increased only in 52w. Increasing of BP during the ontogenic development of SHR evoked both changes in geometry and disproportion in structural composition of the arterial wall. Study was supported by VEGA 2/3145/25.