Fetal behavior, renal sympathetic nerve activity (RSNA), arterial pressure (MAP) and heart rate (HR) were studied 1-3 days after surgery in 7 fetal sheep (aged 127-136 days). Five behavioural states were defined from chart recordings of electrocortical activity (ECoG), eye, limb and breathing movements. Most records were of high voltage ECoG (HV) or low voltage ECoG with breathing (LVB), 6.7 ± 1.7 % were low voltage ECoG with no breathing (LV₀). RSNA was lower in LV₀ (P<0.001) and greater in LV_B than in HV (P<0.05). MAP was lower in both LV states than in HV and when the fetuses went from LV to HV (P<0.001-P<0.03). HR was highest in HV (P<0.001). In HV, LV_B and when the fetus went from LV to HV, MAP and HR were inversely related (P = 0.012-0.003). In LV_B and LV to HV there were direct relationships between MAP and RSNA (P=0.0014, P=0.08) and when the fetus went from LV to HV there was also an inverse relationship between HR and RSNA (P=0.02). Thus fetal RSNA, MAP and HR are affected by behavioral state as is fetal cardiovascular control. The increase in RSNA during fetal breathing showed that there was, associated with fetal breathing activity, an altered level of fetal RSNA.