The aim of the present study was to examine whether self-affirmation promotes acceptance of threatening type 2 diabetes information and risk-testing behaviour. In an experimental study (N = 84), we manipulated self-affirmation by allowing participants to affirm a value that was either personally important or unimportant to them, and measured participants' risk level prior to reading threatening type 2 diabetes information. As dependent variables, we measured message derogation, intentions to do an online type 2 diabetes risk test and online risk-testing behaviour. Findings showed that self-affirmation decreased message derogation, increased intentions to do an online risk test and promoted online risk test taking among at-risk participants. Among participants not at-risk, self-affirmation decreased intentions and online risk test taking. Therefore, it is concluded, that for an at-risk population self-affirmation can decrease defensive responses to threatening health information and promote (online) risk test taking for diseases. © 2009 Taylor & Francis.