Data on the dynamics of the cattle and small stock herds belonging to the Datoga are presented. Overall the Datoga are struggling to survive. They have been alienated from more fertile areas, and consequently they are poor and herd productivity is low. This is due to the low reproduction rate of cattle,and the high commercial offtake rate of both cattle and small stock. The high commercial offtake rate is driven by subsistence needs and most income is used to buy grain and veterinary products. However, there is considerable variation between households, and compared to poor households, wealthy households have a comparatively low offtake rate of livestock, in terms of both mortality and sales; Consequently, they are managing to retain their livestock holdings, or in a few cases to increase the size of their herds. However, wealthy households are in the minority, and the majority of households are caught in a declining cycle of poverty, and will eventually be forced to drop out of the pastoral system. (C) 1999 Elsevier Science Ltd. All rights reserved.