The mechanisation of the dairy industry in New South Wales has proceeded gradually over the past fifty years; however, the rate of increase in the use of mechanised equipment during that period has been far from uniform. The introduction of milking machines at the turn of the century resulted in the first significant use of machinery in the dairy industry. Prior to 1900 the quantity and value of machinery on dairy farms was almost negligible, but by 1920 dairy machinery was valued at almost £1 million, the value having doubled between 1900 and 1910, while between 1910 and 1920 it almost doubled again. Nevertheless, during the twenties the use of machinery did not continue to expand at such a rapid rate as during the years prior to 1920, and with the onset of the depression of the early thirties there was a distinct falling off in new machinery purchases by dairy farmers. In some years of the early and mid-thirties the total value of machinery on dairy farms showed a fall, largely due, no doubt. to the fact that normal replacements were not being made owing to the depressed state of the industry. However, with the outbreak of World War II another period of rapid mechanised expansion began, and still continues. While milk and butter prices remain high and dairy farmers continue to enjoy the present relatively prosperous conditions it is likely that the use of machinery will continue to expand at a rapid rate. The two periods of rapidly increasing mechanisation differ, however, in at least one important respect. In the early part of the century the increased use of machinery was due primarily to the introduction of the milking machine. The present period of expansion is due in part to a further significant increase in the use of milking machines, and again this is the main factor, but also to a significant, and economically important, increase in the use of tractors by coastal dairy farmers. Prior to World War II the ownership of a tractor by the dairy farmer was rare; to-day it has become relatively common.