Background: The central venous catheter (CVC) is a device used for many functions, including monitoring haemodynamic indicators and administering intravenous medications, fluids, blood products and parenteral nutrition. However, as a foreign object, it is susceptible to colonisation by micro-organisms, which may lead to catheter-related blood stream infection (BSI) and in turn, increased mortality, morbidities and health care costs. Objectives: To assess the effects of skin antisepsis as part of CVC care for reducing catheter-related BSIs, catheter colonisation, and patient mortality and morbidities. Search methods: In May 2016 we searched: The Cochrane Wounds Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library); Ovid MEDLINE (including In-Process & Other Non-Indexed Citations and Epub Ahead of Print); Ovid EMBASE and EBSCO CINAHL Plus. We also searched clinical trial registries for ongoing and unpublished studies. There were no restrictions with respect to language, date of publication or study setting. Selection criteria: We included randomised controlled trials (RCTs) that assessed any type of skin antiseptic agent used either alone or in combination, compared with one or more other skin antiseptic agent(s), placebo or no skin antisepsis in patients with a CVC in place. Data collection and analysis: Two authors independently assessed the studies for their eligibility, extracted data and assessed risk of bias. We expressed our results in terms of risk ratio (RR), absolute risk reduction (ARR) and number need to treat for an additional beneficial outcome (NNTB) for dichotomous data, and mean difference (MD) for continuous data, with 95% confidence intervals (CIs). Main results: Thirteen studies were eligible for inclusion, but only 12 studies contributed data, with a total of 3446 CVCs assessed. The total number of participants enrolled was unclear as some studies did not provide such information. The participants were mainly adults admitted to intensive care units, haematology oncology units or general wards. Most studies assessed skin antisepsis prior to insertion and regularly thereafter during the in-dwelling period of the CVC, ranging from every 24 h to every 72 h. The methodological quality of the included studies was mixed due to wide variation in their risk of bias. Most trials did not adequately blind the participants or personnel, and four of the 12 studies had a high risk of bias for incomplete outcome data. Three studies compared different antisepsis regimens with no antisepsis. There was no clear evidence of a difference in all outcomes examined, including catheter-related BSI, septicaemia, catheter colonisation and number of patients who required systemic antibiotics for any of the three comparisons involving three different antisepsis regimens (aqueous povidone-iodine, aqueous chlorhexidine and alcohol compared with no skin antisepsis). However, there were great uncertainties in all estimates due to underpowered analyses and the overall very low quality of evidence presented.There were multiple head-to-head comparisons between different skin antiseptic agents, with different combinations of active substance and base solutions. The most frequent comparison was chlorhexidine solution versus povidone-iodine solution (any base). There was very low quality evidence (downgraded for risk of bias and imprecision) that chlorhexidine may reduce catheter-related BSI compared with povidone-iodine (RR of 0.64, 95% CI 0.41 to 0.99; ARR 2.30%, 95% CI 0.06 to 3.70%). This evidence came from four studies involving 1436 catheters. None of the individual subgroup comparisons of aqueous chlorhexidine versus aqueous povidone-iodine, alcoholic chlorhexidine versus aqueous povidone-iodine and alcoholic chlorhexidine versus alcoholic povidone-iodine showed clear differences for catheter-related BSI or mortality (and were generally underpowered). Mortality was only reported in a single study. There was very low quality evidence that skin antisepsis with chlorhexidine may also reduce catheter colonisation relative to povidone-iodine (RR of 0.68, 95% CI 0.56 to 0.84; ARR 8%, 95% CI 3% to 12%; ; five studies, 1533 catheters, downgraded for risk of bias, indirectness and inconsistency). Evaluations of other skin antiseptic agents were generally in single, small studies, many of which did not report the primary outcome of catheter-related BSI. Trials also poorly reported other outcomes, such as skin infections and adverse events. Authors' conclusions: It is not clear whether cleaning the skin around CVC insertion sites with antiseptic reduces catheter related blood stream infection compared with no skin cleansing. Skin cleansing with chlorhexidine solution may reduce rates of CRBSI and catheter colonisation compared with cleaning with povidone iodine. These results are based on very low quality evidence, which means the true effects may be very different. Moreover these results may be influenced by the nature of the antiseptic solution (i.e. aqueous or alcohol-based). Further RCTs are needed to assess the effectiveness and safety of different skin antisepsis regimens in CVC care; these should measure and report critical clinical outcomes such as sepsis, catheter-related BSI and mortality.