Delayed consequences of acute hypoxia were studied in 60-day-old rat pups. The animals were exposed to acute hypobaric hypoxia on day 10 of embryogenesis. The offspring of intact females served as the control. Reactivity of mesenteric lymphatic vessels to norepinephrine was studied by vital microscopy. The frequency and duration of lymphatic vessel contractions in males significantly increased compared to the control. In females the duration of norepinephrine-induced lymphatic vessel contractions increased, while the frequency and amplitude of contractions and basal vascular tone did not differ from the control.