The clinical and social characteristics of new long-stay (NLS) patients at Friern and Claybury hospitals are described, together with their accumulation rates within health districts in northeast London, and the associations between accumulation rates and social deprivation. There is a fourfold variation between local districts in annual accumulation rates of NLS patients (between 2.5 and 11 per 100,000 population); 0.55 of this variation is accounted for by the Jarman scores of social deprivation, and 0.81 by local rates of unemployment. Other recent British studies support this finding that measures of social deprivation can statistically explain a large proportion of the variation in treated rates of psychiatric morbidity, and may be useful in predicting needs for psychiatric services.