As part of an investigation concerned with investment by both hospitals and local authorities in mental health a number of analyses were made of various published statistics relating to costs and other operating characteristics. In the particular case of spending in mental subnormality hospitals what emerges is a pattern of such surprising variability that it was felt worthwhile presenting the information. It would appear that this particular crude analysis has not been pursued previously despite the existence of the great mass of cost statistics collected, processed, published and circulated within the Health Service. As the Service spent £39·1m. on these hospitals during the fiscal year 1968–69 one might have expected this comparative cost information to have been used in any planning process, particularly when, as will be seen, the magnitude of the variability is so considerable.