The aim of our study is to evaluate in Systemic Sclerosis (SSc) male patients the tadalafil effects on Raynaud's phenomenon and on AM and ET-1 plasma levels. In an open-label study 20 consecutive male patients with SSc were enrolled and received 10 mg of tadalafil daily for 12 weeks. The primary endpoint was the subjective reduction of frequency and duration of Raynaud's attacks measured with a 10-point Raynaud's Condition Score; the secondary aim was to modify Adrenomedullin (AM) and Endothelin-1 (ET-1) plasma levels. After the treatment Raynaud's phenomenon was improved by once-daily tadalafil (decrease of mean number of Raynaud's attacks and of Raynaud's Condition Score) and plasma AM and ET-1 levels decreased. The results of our study lead us to postulate the beneficial effect of adding long term inhibition of Phosphodiesterase type 5 to Systemic Sclerosis' therapy.