The aim of this report is to look at design of tracking tunnel monitoring for stoat control operations. We use. tracking tunnel data from a study in North Okarito forest to develop a stoat-monitoring design and to evaluate the success of different survey protocols. We discuss the importance of understanding statistical power. Power is a measure of the likelihood of reaching the correct conclusion about the success of a monitoring programme. Power is one of the crucial factors that should be considered in designing a monitoring programme. The relative costs of falsely concluding a control operation was successful when it was not, or of falsely concluding a control operation was not successful when it was, need to be carefully evaluated. We recommend for monitoring stoats with tracking tunnels that tunnel-stations be spaced 1 km apart and multiple tunnels be used at each station. The actual survey design for monitoring will depend on the acceptable error rates, the desired level of power, the target percentage kill, and the pre-control stoat density. We have constructed a model to estimate the number of stations and inspections for combinations of type I error rates, power, target percentage kill and pre-control stoat density.