Obstructive apnea during sleep is accompanied by intermittent hypoxia (IH) leading to hypertension and other cardiovascular disturbances. A comparative evaluation of long-term effects of the neonatal IH on the cardiovascular functions was performed in normotensive Sprague-Dawley and spontaneously hypertensive rats (SHR). The newborn rats were placed for 30 days to conditions of IH (8% and 21% O2, alternating every 90 s for 12 h/day). Control groups of rats were constantly kept in normoxia. By 6 months, in the spontaneously hypertensive rats exposed to IH at the period of wakefulness there was a statistically significant increase (as compared with control) of the systolic (185.8 ± 1.7 and 169.9 ± 1.4 mm Hg, correspondingly, p <0.010 and the diastolic pressure (96.2 ± 4.9 and 86.0 ± 2.6 mm Hg, correspondingly, p <0.01). During sleep, the systolic and diastolic pressure in these rats was higher than in control animals by 10 mm Hg (p <0.01) and 12 mm Hg (p <0.01), its decrease during sleep being absent. In SH