Abstract: In the present study, cAMP and cGMP phosphodiesterase inhibitory (PDEI) activities of the ethanolic extracts of nineteen plants of Traditional Iranian Medicine (TIM) with aphrodisiac effects were investigated. The plants were extracted in a similar way and then three concentrations (0. 1, 1, 5 mg mL-1) from each were tested for PDEI activity against control and sildenafil. Among plants tested, 8 including Allium cepa, Trigonella foenum-graecum, Brassica rapa, Alpinia officinarum, Tribulus terrestris, Urtica pilulifera, Linum usitatissimum and Zingiber zerumbet exhibited a significant dose-dependent cAMP-PDEI activity and 6 including A. cepa, A. officinarum, T. terrestris, L. usitatissimum, Withania somnifera and Z. zerumbet gave a remarkable dose-dependent cGMP-PDEI effects in comparison to control. Among tested herbs, Zingiber officinalis and Peganum harmala at dose of 5 mg mL-1 demonstrated better cGMP-PDEI in comparison to sildenafil. The results of this study give idea for discovery of safe and better drugs in management of erectile dysfunction.