A deficit of social cognition in bipolar disorder has been shown, even when patients are stable. This study compares the attribution of intentions (social-cognitive bias) in a group of 37 outpatients with bipolar disorder with 32 matched control subjects. Bipolar patients scored significantly higher in the Ambiguous Intentions Hostility Questionnaire, showing an angry and intentionality bias (P = .001, P = .02). Differences in blame scale and hostility bias did not reach statistical significance, but a trend was found (P = .06). Bipolar patients with depressive symptoms presented a higher score in the angry bias scale (P = .03) and aggressivity bias scale (P = .004). The global functioning (GAF) correlates significantly with intentionality (P = .005), angry (P = .027), and aggressivity (P = .020) biases. Bipolar patients show a social-cognitive bias that may play a role in their functional outcome.