The Raynaud's phenomenon often accompanies systemic rheumatic diseases and is also known as a vascular side effect of chemotherapy. Therapy of the Raynaud's phenomenon with nitrates or calcium-channel-blockers is rarely beneficial. In contrast, the PDE-V-inhibitor sildenafil seems to be effective in these patients. For the first time we report on a patient with Raynaud's phenomenon due to chemotherapy not responding to sildenafil but to the new PDE-V-inhibitor tadalafil in an equivalent dosage. Measurement with a laser Doppler revealed an increased blood flow and a reduction of symptoms. Therefore, therapy of Raynaud's phenomenon with the new PDE-V-inhibitor tadalafil seems to be an effective treatment option in patients not responding to sildenafil.