Somatisation disorder (Briquet's syndrome) is a recent addition to psychiatric nosology. It represents an attempt to describe a syndrome of 'hysteria', the term initially applied to this polysymptomatic disorder by Guze and his colleagues. The manner of identification of this syndrome, however, has been the subject of criticism. This brief review suggests that the ideas of Janet, who worked at Salpetriere 30 to 40 years after Briquet, may provide a more precise approach to diagnosis. Furthermore, his hypotheses about predisposition to this disorder are seen to offer a preliminary way towards its understanding. Recent experimental evidence lends some support to Janet's hypotheses.