We compared haemodynamic and peripheral vasomotor responses to lower body negative pressure (LBNP) in cardiac transplant recipients who had undergone bicaval anastomoses, involving right atrial deafferentation (-RA), and the conventional procedure in which some atrial baroreceptor afferents remain intact (+RA). We measured mean forearm blood flow (FBF) responses using Doppler/ultrasound during 3 randomised trials involving 0 (baseline), -20 and -40 mmHg LBNP in 15 transplant recipients (9 -RA, 6 +RA) and in 8 healthy matched controls. A significant effect of LBNP on FBF existed between control and transplant groups (P<0.05; 2-way ANOVA). Mild LBNP (-20 mmHg), significantly decreased FBF by 29.7 ± 10.0 % relative to baseline in +RA subjects (P<0.05), whereas the 17.7 ± 10.3% decrease in -RA subjects was not significant. In response to -40 mmHg LBNP, FBF significantly decreased in control (42.4 ± 4.6%, P<0.05) and +RA subjects (33.3 ± 11.4%, P<0.05) with no significant change in the -RA group. The response of systolic blood pressure (SBP) to -40 mmHg significantly differed between groups (P<0.05): -RA subjects decreased significantly (P<0.05) whilst the decrease in SBP in +RA subjects did not achieve significance and control subjects exhibited an increase. The heart rate increase from baseline to -40 mmHg was significantly attenuated in -RA relative to controls and the +RA group (P<0.05). The present study demonstrates that atrial deafferentation impairs reflex vasomotor control of the circulation in response to low- and high-level LBNP, indicating that atrial deafferentation may contribute to abnormal arterial pressure regulation.