Some of the literature on anxiety states is reviewed, particularly from the point of view of measurement of amount, and prognosis. A review is presented of a number of cases which were followed up, tables are given, and results summarized. The following conclusions are drawn. Anxiety states may persist unchanged for ten years and over, and only a small percentage pass on into hypochrondriasis. The prognosis is good if the duration is under two years, and poor, but not hopeless, if of longer standing. The chance of returning to work proved to be 80 per cent. of all cases. If the anxiety does not alter the mode of life, the prognosis is better, but the psychopathic personalities do not do well. No evidence of increased susceptibility to organic disease was found in the cases under consideration.