Objective Although increasing attention is directed at identifying biological mechanisms underlying cognitive changes observed in cancer patients without central nervous system disease following chemotherapy, psychological factors that can contribute to these cognitive changes are much less studied. Methods In an online experiment, the influence of informing patients about the association between cognitive problems and chemotherapy on self-reported cognitive functioning and neuropsychological test performance was investigated. Results Cancer patients treated with chemotherapy (n = 150) reported higher levels of cognitive complaints after receiving such information (M = 21.20) than without such information (M = 18.98; p = 0.032). No difference was found for patients without (a history of) chemotherapy (n = 86; M = 18.85 vs. 20.08; NS). A similar interaction pattern was observed on a word-learning test. Patients treated with chemotherapy recalled fewer words after being informed about the association between cognitive problems and chemotherapy (M = 24.44) than without such information (M = 27.63; p = 0.010). No difference was found for patients not treated with chemotherapy (M = 26.35 vs. 25.38; NS). Conclusion Patient information may induce a stereotype threat, which affects self-reported cognitive function and neuropsychological test performance in cancer patients for whom this information is relevant. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.