[eng] Peripheral venous catheterization is a common technique in hospitals which is not always successful, result-ing in multiple punctures and degradation of the vessels. This scenario, which we have termed'difficultperipheral venous access', is associated to delays in care, obtention of samples or diagnosis, as well as ahigher use of central catheters.This study intends to identify risk factors associated to the incidence of'difficult peripheral venous access'inadults at hospital.We designed a systematic review of published studies (protocol PROSPERO 2018 CRD42018089160). Weconducted structured electronic searches using key words and specific vocabulary, as well as directedsearches in several databases. After validity analysis, we selected 7 studies with observational methodology.We found great variability in the definition of'difficult peripheral venous access'and in the variables pro-posed as risk factors. Statistically significant factors through studies include demographic and anthropomet-ric variables (gender, Body Mass Index), as well as medical and health conditions (diabetes, renalinsufficiency, parenteral drug abuse, cancer chemotherapy), together with variables related to the vein orvascular access (vein visibility and palpability, vessel diameter, previous history of difficulty). Some studieshave also considered variables related to the professional performing the technique.Meta-analyses were carried out for gender and obesity as potential risk factors. Only obesity appeared as astatistically significant risk factor with OR of 1.48; 95% CI (1.03 to 1.93;p= 0.016). Methodological heteroge-neity prevented the development of further meta-analyses.It is essential to design future studies with diverse hospital populations, in which a wide selection of poten-tial risk factors can be studied in a unique analysis. Our work identifies the most relevant variables thatshould be included in those studies.