Large doses of corticosteroids have pharmacological actions which include suppression of the local and general manifestations of inflammation, inhibition of antibody formation and shrinkage of lymphatic tissues. These actions possibly with others less well defined led to corticosteroid therapy being tried in patients with reticuloses. Any benefit produced must be considered in relation to the complications and dangers of this form of treatment. Experience of the last ten years has emphasised the dangers of giving big doses of these drugs for months or years. A number of chemically modified corticosteroids are now available and the choice of the best preparation for any patient may present some difficulty. The first modification was that which changed cortisone and hydrocortisone to Prednisone or Prednisolone. Prednisone has five-fold increase of therapeutic potency but no increase of salt-retaining action. Prednisone 30 mg per day does not cause oedema whereas the equivalent dose of cortisone (150 mg per day) will do so unless the patient is on a very low sodium intake. If the dose of Prednisone has to exceed 60 mg per day oedema may result. Methyl Prednisolone has the same potency as Prednisone and Prednisolone but less salt-retaining action. Triamcinolone produces headache and flushing and also reduces the appetite, this may be helpful if the patient is putting on too much weight. Muscle weakness is more common with Triamcinolone, this may be due to reduction of protein intake and a bigger negative nitrogen balance.