Androgen receptor is present in heart. There is evidence testosterone acts directly on the myocardium. There is also evidence that testosterone enhances the cardiac response to alpha (α1) and beta (β1)-adrenoceptor stimulation. We hypothesize that testosterone at physiological concentration enhances cardiac contractile functions through modulating adrenoceptor stimulation. Three groups of male Sprague–Dawley rats namely sham control, gonadectomized (GDX) rats and GDX with physiological testosterone replacement (GDX+T) were used. Hearts and ventricular myocytes were isolated. α1 (phenylephrine, 1×10−6 mol/L)/β1 (isoproterenol, 1×10−7 mol/L)/selective β2 (salbutamol, 1×10−6 mol/L; fenoterol, 1×10−6 mol/L) adrenoceptor agonists were administered respectively to both preparations. Electrical-induced Ca2+ transient (E[Ca2+]i) was measured in left ventricular myocytes while cardiac contractile variables (left ventricular developed pressure, dP/dtmax, heart rate and left ventricular end diastolic pressure) were determined in the isolated perfused hearts. Protein expression of adrenoceptor was also determined. Administration of agonists increased amplitude and decreased T50 of E[Ca2+]i, LVDP and ±dP/dtmax in all groups. The increase was significantly greater in sham than the GDX group. GDX+T reversed these effects. Nine weeks of castration also results a significant decline in expression of α1A-, β1- and β2-adrenoceptors. The present study provides first evidence that testosterone at physiological concentration enhances cardiac contractile responses to stimulation of cardiac adrenoceptors.