HYDROCORTISONE is sometimes used as a necessary treatment for many diseases. But unfortunately, it usually causes osteoporosis when used for long periods of administration even with normal doses. It reduces variations in calcium and phosphate contents in bones. The aim of the present work is to study the effects of long period hydrocortisone treatment on the bone composition of rat hind-leg, Three techniques were used in this study: X-ray imaging to analyze the bone density, molecular spectromphotometer for determining bone composition and histological study to clear the bone structure. The obtained data showed variations in calcium and phosphate contents during the hydrocortisone treatment periods, which reached maximum changes after three weeks of treatment. The obtained results by X-ray images indicated changes in the bone density which were supported and found in good agreement with that obtained by both spectrophotometric analysis and structural changes.