Background: Raynaud’s phenomenon is induced by excessive vasoconstriction of the peripheral microcirculation in response to environmental factors, essentially cold, but also stress or emotions. The objective of the present study is to evaluate the impact of global warming on the worldwide prevalence and severity of Raynaud’s phenomenon over the 21 st century. Method: We first estimated the correlation between average temperature and prevalence and severity of Raynaud’s phenomenon. Then, we mapped the prevalence and the severity of Raynaud’s phenomenon worldwide at Christmas 1999 using historical data and, using climate projections from the Inter-Sectoral Impact Model Intercomparison Project, we predicted the prevalence and severity of Raynaud’s phenomenon at Christmas 2099 according to four greenhouse-gas emission scenarios. Results : The prevalence of Raynaud’s phenomenon in the general population is expected to decrease by 0.5% per degree Celsius increase. Furthermore, patients are expected to suffer from one less attack per week for each increase of 2.5 degrees Celsius. Conclusions : Our study shows that global warming may have a significant impact on the prevalence and the severity of Raynaud’s phenomenon over the 21 st century. However, as expected, this will greatly depend on the level of greenhouse-gas emissions.