Carvacrol is a monoterpene found in essential oils from various plants. Several pharmacological properties have already been described for carvacrol, including antimicrobial, anti-inflammatory, anticarcinogenic, antioxidant, vasorelaxant and hypotensive activities. The present study evaluated the effect of carvacrol on hypertensive rats with erectile dysfunction. Twelve-week-old spontaneously hypertensive rats (SHR) were treated with vehicle, carvacrol (50 or 100 mg/kg/day) or sildenafil (1.5 mg/kg/day), intragastrically, for four weeks. Wistar Kyoto (WKY) rats were used as the normotensive controls. All substances tested reduced systolic blood pressure during the treatment period. The intracavernosal pressure/mean arterial pressure ratio of the hypertensive rats was improved by carvacrol and sildenafil treatments. In isolated rat corpora cavernosa, the acetylcholine- and SNP-induced relaxation responses were significantly increased by carvacrol or sildenafil treatments. In SHR corpora cavernosa, treatment with carvacrol attenuated the hypercontractility induced by phenylephrine or electrical field stimulation. Phe-induced hypercontractility in the presence of tempol was not altered when compared to the response induced by carvacrol alone. In rat corpora cavernosa fluorescence intensity emitted by the DHE probe was significantly reduced in SHR treated (carvacrol or sildenafil) groups when compared to that emitted in the SHR-CTL. This study showed that carvacrol improves the erectile function of hypertensive rats and reduces endothelial dysfunction, smooth muscle cell hypercontractility and superoxide anion generation.