Glucocorticoids (GCs) are widely utilized in medical practice to combat diseases having an inflammatory ele­ment. The aim of the present study is to throw light on the effects of risedro-nate sodium (Ris)on the architecture of the tibiae of the albino rats on beta-methasone (Bet) therapy. Thirty adult male albino rats (200-250 gm) were used in this study. They were ran­domized into three equal groups:control, Bet-treated and both Bet- and Ris-treated. At sacrifice, small pieces of the decalcified tibiae were processed to prepare paraffin sections stained with haematoxylin and eosin (H&E) and Masson's tri-
chrome. Other ultra-thin sections stained with uranyl acetate and lead citrate for EM study were, also, pre­pared. The tibiae of the Bet-treated rats showed an apparently marked decrease in the amount of collage-nous fibres, separation and thinning of the pesiosteum, notches at the bone surfaces, resorption cavities filled with granulation tissue, irregular sizes and distribution of Haversian canals as well as non-homogenous dark and pale areas of the matrix. Ul­tra-structural ly, the osteoblasts got degenerated. They lost their process­es and became smooth. Their cyto­plasm lacked its organelles and gained many vacuoles