Experimental studies show that training people to attend to negative stimuli makes them more likely to respond with greater anxiety to stress. The present study investigated this effect in students using measures of cardiovascular responses to stress and examined whether individual differences influence the impact of attention training on stress responses. Using a standard dot probe task, 30 participants underwent negative attentional bias training and 34 participants underwent anti-negative training before completing a stressful speech task. Results indicated that, overall, participants exhibited acclimatization to the procedures (indicated by a dip in blood pressure post-training) and normal stress responding (indicated by elevated blood pressure in response to stress; p < .001). However, consideration of participants' scores for neuroticism/emotional-stability revealed important differences in how the intervention impacted on cardiovascular profiles (p = .008). For participants with high neuroticism scores, the negative attentional bias intervention elicited more exaggerated stress responding than the anti-negative intervention. For those with low neuroticism scores (i.e., emotionally stable participants), the anti-negative intervention was associated with elevated post-intervention blood pressure and higher blood pressure reactivity to stress. These findings provide evidence of the impact of attentional bias manipulation on physiological stress reactivity and suggest the effect is highly contingent on individual temperaments.