Alexithymia has been linked to various disorders, including compulsive behaviors, anxiety disorders, and physical conditions with or without symptoms. It has been hypothesized that these disorders result from the alexithymic inability to differentiate and elaborate affect, which gives rise to physiological arousal and a negative subjective state, which are not regulated by psychological strategies. We tested these hypothesized mechanisms by comparing 42 alexithymic subjects with 42 sex- and race-matched nonalexithymic subjects on physiological and subjective responses to an autogenic relaxation exercise and three different laboratory stressors. Alexithymic subjects had tonically greater electrodermal activity and reported more arousal and displeasure in general than nonalexithymic subjects. Groups did not differ in the degree to which they relaxed, but alexithymic subjects reported less enjoyment, of, less involvement in, and poorer imagery during relaxation. All three stressors evoked reactivity, and alexithymic women had less heart rate change when viewing disgusting scenes than did nonalexithymic women; in general, however, groups did not differ in reactivity or recovery to the stressors. We find some support for the hypothesized mechanisms of alexithymia, and we suggest specific links between alexithymia and clinical disorders.