Some few months ago the National Agricultural Advisory Service, South West Sub-Centre, encountered several farms in their area where failure to reach the required standard for designated milk appeared to be connected in some way with pronounced pitting corrosion of aluminium alloy milking buckets, and, on the suggestion of Dr A. R. T. Mattick of the National Institute for Research in Dairying, Reading, the authors of this note were given the opportunity of examining a corroded pail and of tracing the source of the corrosion, if possible.