Objective To study the β3-adrenoceptor (β3-AR) in heart and lungs of elderly heart failure (HF) rats.Methods Forty-eight elderly HF Wistar rats were included in this study.A HF model of rats was established by ligating the aorta.The rats were divided into sham operation group (n=24) and HF group (n=24).The rats in each group were further divided into 4 subgroups at weeks 5,7,9 and 11 after operation (6 in each group).The hemodynamics,pathology and expression of β3-AR mRNA and protein in heart and lungs were detected at weeks 5,7,9 and 11 respectively after operation.Results The heart rate,LVESP,and dp/dtmax were significantly lower in HF group than in sham operation group at weeks 9 and 11 after operation while the LVEDP was significantly higher in HF group than in sham operation group at weeks 5,7,9 and 11 after operation (P＜0.01).Pulmonary edema occurred at week 7 after operation and myocardial necrosis was detected at week 9 after operation.The expression level of β3-AR mRNA in lungs was significantly lower in HF group at weeks 5,7,9 and 11 than at week 2 after operation (P＜0.05).The expression level of β3-AR mRNA in heart was significantly higher in HF group than in sham operation group at weeks 9 and 11 after operation (1.21±0.26 vs 0.98±0.22,1.26±0.23 vs 1.05±0.24,P＜0.01).Conclusion The β3-AR mRNA expression is downregulated in the lungs and upregulated in the heart.