This paper develops a method for estimating the value of additional information to the individual livestock producer. In doing so it considers as part of the decision made by the farmer to vaccinate animals against B. bovis the decision to collect information on the health status of his herd using serological sampling. Bayesian decision theory is used in this paper. Bayesian decision theory combines statistical and economic information to assist in identifying optimal management policies. This approach has been used in a number of situations in animal health decision making, for example Williamson, 1975; Elder and Morris, 1986; Fetrow et al., 1985; Parsons et al., 1986. This paper firstly examines the private use of animal health information then the relationship between the cost of gathering information and the value of the information. This is followed discussion about decisions to gather additional information. A method to determine the optimal sample size is examined and applied.