Some systemic painful syndromes are often unclassifiable because of their unconvincing clinical features and often labelled as hysterical, psychogenic or atypical manifestations of fibrositis or rheumatism. Some of these are grouped in a new syndrome called systemic "non-organic central pain (NOCP)". The most salient features of systemic NOCP are: a) diffused pain subsequent to and accompanying idiopathic headache, b) characteristics of pain similar to, if less pronounced, than organic central pain of the thalamic syndrome and c) decentralization supersensitivity to monamines. Systemic NOCP was diagnosed in 14 patients admitted to the hospital for serious disabling systemic pains. In 7 of these, an impressive increase of vein sensitivity to noradrenaline, dopamine, tyramine, and even more so to 5-HT (up to 1000 times), was detected. Because this supersensitivity involves different monamines, it should be considered a decentralization process. This decentralization supersensitivity is related to the mechanism of pain and is hypothesized as a non-organic, biochemical, usually genetic impairment of the antinociceptive system. Migraine, tensional and other idiopathic headaches are more commonly considered expressions of NOCP. The clinical importance of NOCP is emphasized by its high neuroticizing capacity as is commonly seen in other chronic, recurrent pain disorders.