Acute stress and decision making (DM) interact in life – although little is known about the role of ambiguity and risk in this interaction. The aim of this study is to clarify the effect of acute stress on DM under various conditions. Thirty-one young healthy men were randomly distributed into two groups: experimental and control. DM processes were evaluated before and after an experimental session. For the experimental group, the session consisted of an acute stress battery; and the protocol was similar for the control group but the instructions were designed to minimize acute stress. Cardiovascular variables were continuously recorded 30 minutes before the DM tasks and during the experimental session. Cortisol, glucose, mood responses, and personality factors were also assessed. Acute stress was found to enhance disadvantageous decisions under ambiguous conditions (F(1, 29) = 4.16, p = .05, η2
= .13), and this was mainly explained by the stress induced cortisol response (26.1% of variance, F(1, 30) = 11.59, p = .002). While there were no significant effects under risky conditions, inhibition responses differed between groups (F(1, 29) = 4.21, p = .05, η2
= .13) and these differences were explained by cardiovascular and psychological responses (39.1% of variance, F(3, 30) = 7.42, p < .001). Results suggest that DM tasks could compete with cognitive resources after acute stress and could have implications for intervention in acute stress effects on DM in contexts such as addiction or eating disorders.