OBJECTIVE: To determine the effectiveness of a modulated acoustic startle reflex paradigm with emotional imagery in studying physiological changes associated with emotional responses in persons with traumatic brain injury (TBI). SETTING: Outpatient rehabilitation hospital. PARTICIPANTS: Six individuals with moderate to severe TBI. Mean age was 32 years and mean years postinjury were 9.9. METHOD: The modulated acoustic startle reflex procedure involved imagery of emotional scripts (joy, anger, fear, and neutral) followed by a startle noise, versus startle noise alone (no script). MEASURES: Eyeblink and skin conductance response, subjective arousal and valence ratings of the scripts, and general anger questionnaire. RESULTS: Startle blink responses following anger imagery were significantly smaller than those following fear (P =.006) and neutral (P =.023) imagery. Skin conductance response did not change significantly based on the content of the scripts (P =.070). CONCLUSIONS: Large startle blink responses indicate avoidance of a stimulus. Our findings suggest that participants with TBI did not have an avoidant reaction to anger-inducing stimuli. Skin conductance response findings may imply arousal impairments. The modulated acoustic startle reflex was effective in measuring emotional responses; however, larger studies comparing persons with TBI with control groups are needed to further explore these findings.