Naturally-occurring androgens such as testosterone are important in regulating growth in entire male animals (e.g. Galbraith & Topps, 1981). Synthetic steroids with androgenic properties when given exogenously are also known to alter growth of sheep and cattle. Knowledge on the effects of these androgens on body composition and on their mode of action is Inadequate. The major objective of this study was to compare their effects on growth performance and body composition and to relate the responses obtained to changes in certain characteristics of the endocrine system and glucocorticoid receptors in muscle. The steroids used were testosterone (naturally occurring), trenbolone acetate (TBA) (synthetic compound) and nandrolone (19 nor-testosterone - produced synthetically and considered not to occur naturally in castrate male sheep).