It has been shown that people under threat to self-worth exhibit negative implicit attitudes toward minority outgroups (e.g., African Americans in North America) (Spencer, Fein, Wolfe, & Dunn, 1998). But it has not been shown that people under such threat exhibit negative implicit attitudes toward outgroups which are not likely to be negatively evaluated (e.g., women). We conducted an experiment to examine whether male participants under threat to self-worth would exhibit implicit ingroup bias related to gender by using Implicit Association Tests (IATs.) Participants received either self-image threatening feedback about initial tests or no feedback (threat vs. non-threat). They then completed gender attitude IATs. The results showed that participants exhibited stronger implicit ingroup biases related to gender in the threat condition than in the nonthreat condition. The role of threat to self-worth in men's implicit gender attitude is discussed.