Compared to the study of adult fears, childhood fears have not been extensively investigated in terms of their psychophysiological bases. However, limited findings suggest that children exhibit psychophysiological reactivity to fear-eliciting stimuli. Other data suggest that fear imagery produces psychophysiological arousal and that youngsters may be trained in fear imagery. Psychophysiological measures have also been used in the evaluation of desensitisation as seen in a limited number of case studies, single-subject experimental analyses and group outcome comparisons. In general, psychophysiological changes have been reported that are suggestive of reduced autonomic arousal. Methodological and theoretical issues are discussed including the selection of psychophysiological measures and the desynchrony between measures of fear.