The term 'angry back syndrome' (ABS) was coined by Mitchell in 1975. It was stated that a strong positive patch test reaction could create an 'angry back' which becomes hyper-reactive to other patch test challenges. The present study investigated whether the ABS is a generalized state of hyper-reactivity of skin, whether it is a localized hyper-reactivity of skin, i.e. only in the close proximity to a strong patch test reaction, whether it is an individual specific phenomenon and if ABS is a reproducible phenomenon. The studies failed to demonstrate any generalized or localized change in the reactivity of the skin. This left the possibility that ABS might be a rare, and individual-specific phenomenon. However, even in the subjects who had previously been diagnosed as having ABS we failed to reproduce the angry back.