Compared with European Red deer, Scottish Red deer stags are remarkably small. Previous research has shown that this may be primarily due to nutritional, rather than genetic reasons. The present study tested the hypothesis that poor nutrition, especially during the first winter of life, prevented the stags from reaching their genetic potential size. The study was carried out at Glensaugh Research Station on 20 newly weaned Red deer assigned to either of two groups, one fed a high plane of nutrition during the winter, the other a low plane. The trial began in December 1977 and in May 1978 both groups were released into a 200 acre paddock. In September 1978 some of each group were slaughtered. Despite considerable compensation by the low plane winter nutrition group there were significant differences in live weight, antler length and carcass weight at slaughter. It is considered that Scottish Red deer stags reach the maximum size that the environment can maintain despite this being far below their genetic potential.