This paper will discuss why and how social network sites ought to be used in surrogate decision making (SDM), with focus on a context like Singapore in which substituted judgment is incorporated as part of best interest assessment for SDM, as guided by the Code of Practice for making decisions for those lacking mental capacity under the Mental Capacity Act (2008). Specifically, the paper will argue that the Code of Practice already supports an ethical obligation, as part of a patient-centred (...) care approach, to look for and appraise social network site (SNS) as a source of information for best interest decision making. As an important preliminary, the paper will draw on Berg’s arguments to support the use of SNS information as a resource for SDM. It will also supplement her account for how SNS information ought to be weighed against or considered alongside other evidence of patient preference or wishes, such as advance directives and anecdotal accounts by relatives. (shrink)