The current study examined the role of thought suppression in spider phobia. Spider phobic (n = 41) and non-phobic (n = 40) subjects were asked to monitor their thoughts for three 5 min periods. During the first period, all subjects were instructed to ''think about anything''. During the second period, half of the subjects received suppression instructions (i.e., subjects were explicitly asked ''not to think of spiders''), whereas the other half once again received instructions to ''think about anything''. During the third period, all subjects were instructed to ''think about anything''. Spider-related thoughts were monitored on-line. Also, subjects retrospectively estimated the amount of time they had spent thinking about spiders. Overall, spider phobics reported higher levels of spider-related thoughts than non-phobic subjects. Furthermore, phobic subjects tried harder to suppress spider-related thoughts than non-phobic subjects. Finally, although some evidence was found for the counterproductive effects of thought suppression, its contribution to the frequency of spider-related thoughts was minimal.