Funds for public programmes for control of animal diseases are limited and especially so in less developed countries. Therefore it is important from an economic point of view to get the 'best value for money' from such control expenditure. After briefly reviewing the economic rationale for government intervention in control of animal diseases, this paper provides a basic analysis of the economics of optimal private and public decisions about control of animal diseases. It explores the role for cost-benefit analysis in this decision- making, taking into account informational constraints and the resource demands of multiple diseases requiring control. The analysis is illustrated by examples and issues from Thailand and pays particular attention to foot-and-mouth disease. A research proposal to help assess public programmes for the control of animal disease in Thailand is briefly sketched. The need for a dynamic approach to disease-control policy is emphasised.