Despite the hypothesized link between arousal and behavior in persons with autism, there is a lack of idiographic research that directly assesses arousal responses to novel stimuli or social situations in this population. The current study used heart rate as a measure of sympathetic activity to compare arousal responses to the presentation of potentially stressful situations in five persons with autism and five age- and sex-matched typically developing individuals. Findings revealed that the group with autism showed significant responses to stressors only 22% of the time compared to the typically developing group, which showed significant responses 60% of the time. Interpretation of these results and methodological considerations for future research on arousal in persons with autism are discussed.