Muscle sympathetic nerve activity (MSNA) is modulated by respiration such that lung stretch receptor activity during inspiration inhibits sympathetic activity. Respiratory sympathetic coupling is preserved in healthy older versus younger men (1), but whether a similar preservation occurs in healthy postmenopausal versus premenopausal women is not known. Thirteen postmenopausal women (PMW; 55 [9] years), 12 young women (YW; 25 [5] years) and 12 young men (YM; 26 [7] years) gave written informed consent to participate (demographic data available for 9/13 PMW, 11/12 YW, 12/12 YM). YW took part in the early follicular phase of the menstrual cycle or low-hormone phase of oral contraception. PMW had been amenorrhoeic for at least one year without hormone replacement therapy. MSNA (peroneal microneurography), respiration (respiratory belt), heart rate (ECG) and continuous blood pressure (brachial intra-arterial catheter) were recorded over five minutes of quiet rest. MSNA was sampled during 20 % intervals of inspiration and expiration and quantified as two respiratory phases: mid to late expiration (60-100 % of expiration and 0-60 % of inspiration) and inspiration to post-inspiration (60-100 % of inspiration and 0-60 % of expiration) (1). Two-way mixed ANOVA tested for an interaction between group and respiratory phase, whilst one-way ANOVA or Kruskal-Wallis test tested for group differences in demographic, haemodynamic and percentage change data. Data are presented as mean ± SD or median [interquartile range]. Body mass index (24.2±2.5, 23.7± 1.0, 24.7± 2.2 kg/m2, p=0.317), mean arterial pressure (97 [14], 98 [12], 88 [8] mmHg, p=0.065), heart rate (64±7, 62±10, 58±9 beats/min, p=0.247) and breathing rate (13 [5], 14 [2], 13 [6] breaths/min, p=0.818) were similar in PMW, YW and YM. Overall MSNA burst incidence was higher in PMW (79 [17] bursts/100 HB) versus YW (53 [13] bursts/100 HB, p<0.0005) and YM (51 [11] bursts/100 HB, p<0.0005). There were no significant interactions between group and respiratory phase for heart rate, sum of burst area/s, or mean burst area/s, however all showed significant main effects of group and respiratory phase. There were significant interactions between group and respiratory phase for burst incidence and burst frequency (p=0.004 and p=0.029). Simple main effects analysis revealed that PMW showed a higher burst incidence versus YW and YM during both respiratory phases (mid to late expiration 83±12 versus 62±17 and 65±11 bursts/100 HB, p=0.002 and p=0.009; inspiration to post-inspiration 72±12 versus 39±11 and 41±8 bursts/100 HB, p<0.0005 and p<0.0005), with similar results seen for burst frequency. However, PMW exhibited a smaller percentage reduction in MSNA during inspiration to post-inspiration versus mid to late expiration than YW and YM (-10.3 [9.7] versus -37.9 [16.8] and -38.2 [11.6] % change in burst incidence, p=0.003 and p=0.001; -10.9±10.6 versus -31.6±14.8 and -33.2±14.5 % change in burst frequency, p=0.001 and p=0.001). These data indicate that, whilst respiratory sympathetic coupling is preserved in PMW, inspiratory inhibition of MSNA is smaller in PMW versus YW and YM.