In a 5 year radiotracking study of 55 falcons on the Wairau Plain, Marlborough, the causes of death in 21 birds were identified. Of these, 10 (47%) falcons were electrocuted (7 juvenile females, 1 adult female, 1 juvenile male, and 1 adult male). Seven of the 10 poles were fitted with transformers. This level of mortality is thought to be too high to sustain a population of falcons. Suggestions are made how to mitigate the problem.