Purpose We used apparent co‐witness intoxication as a way to examine the effect of source credibility on the acceptance of misinformation from a co‐witness. Methods Alongside an experimental confederate, individual participants (N = 100) watched a clip involving two simulated thefts. Immediately beforehand, half of the participants watched the confederate consume what appeared to be three alcoholic beverages. During a subsequent discussion with the participant, the confederate introduced two pieces of misinformation about the clip. In the absence of the confederate, participants were then interviewed before completing a target‐absent line‐up task. Results As expected, misinformation impaired participants’ verbal reports, and misinformation about appearance impaired line‐up performance. Overall susceptibility to misinformation was not significantly related to co‐witness condition, or to participants’ ratings of the confederate's intoxication or ability to accurately complete the tasks. On individual items, however, co‐witness condition appeared to exert some influence on misinformation acceptance if the participant's pre‐misinformation response was discrepant with the misinformation, but not when it was ‘don't know’. Conclusions It is possible that effects of source credibility on misinformation acceptance may depend, at least to some extent, on the presence of a clear discrepancy between the misinformation and the witness's recollection.