Spontaneously hypertensive rats (SHR) represent a genetic model of human hypertension and hypertriglyceridemic (HTG) rats represent a model of human metabolic syndrome X. We compared blood pressure (BP), cardiac hypertrophy and age-dependent morphological changes of carotid artery (AC) in 3-week (3w), 17-week (17w), and 52-week-(52w) old SHR, HTG and Wistar rats. The animals were perfused with a glutaraldehyde fixative (90 mm Hg - 3w, 120 mm Hg -the rest of groups). AC was exised and processed for electron microscopy. SHR vs. Wistar rats: BP of 3w did not differ, in later periods it was increased; cardiac hypertrophy was found in all groups; wall thickness (WT) and cross sectional area (CSA) in 3w did not differ, in later period they were increased; inner diameter (ID) in 3w was decreased, in later periods did not differ; WT/ID was increased during the whole ontogenic periods. HTG vs. Wistar rats: BP was increased in all periods; cardiac hypertrophy was observed in 3w and 17w; WT in 3w was decreased, in 52w it was increased; CSA and ID were decreased during the whole ontogeny; WT/ID was increased only in 52w. Dispropotion between development of BP, cardiac hypertrophy and geometry of AC in SHR and HTG rats were observed during ontogeny. Supported by VEGA 2/3145/25 and SP 51/0280900/0280901