Objective Telangiectasias of the lower legs are intradermal dilatations of the subpapillary venous plexus, but their pathophysiology and risk factors are still largely unknown. The purpose of this review is to summarize the current knowledge on the pathophysiology and risk factors for telangiectasias. Methods A systematic review of the literature indexed in Medline completed with textbooks and European phlebology journals from the French, Swiss, and German phlebology societies was performed. Results A multitude of risk factors and several pathophysiological hypotheses, such as reflux, arterio-venous micro-shunts, parietal, and connective tissue abnormalities, are described in the literature. The different hypotheses are discussed and put in a clinical perspective, in particular their therapeutic implications for phlebologists. Conclusion In conclusion, pathophysiology and risk factors of telangiectasias are still largely unknown, and a better understanding could improve treatment results and reduce recurrence.