In previous studies on red deer we have found that the dominant individual males of a socially stabilized group tend to cast and/or clean antlers earlier and produce larger antlers than subordinate ones. This is important because male red deer with largeantlers had increased lifetime breeding success. Deer males gaining higher rank through fighting more other males exhibited enhanced growth of that part of the antler that was just developing. This changed if the male lost his position. We suggested that the relationship between rank and antler growth may be mediated most of all by testosterone. The more dominant the stag, the higher the seasonally attained levels of androgens, the greater the enhancement of antler tissue formation. We recorded that the higher the level of aggression among the males, the closer the relationship between rank and timing of the antler cycle. In situations with a linear hierarchy, rank position and antler casting are highly correlated. However, in complicated hierarchieswith multiple triangular relationships the correlation dropped below the level of significance. The aim of this proposed project is to elucidate how experimentally changed social environment affects hormonal regulation of antler growth.