✓ Considerable difference of opinion has arisen as to whether intravenously administered steroids affect cerebrospinal fluid (CSF) production in the acute laboratory animal undergoing ventriculocisternal perfusion. Our experiments with ventriculocisternal perfusion in dogs indicate that, when given intravenously, neither dexamethasone, methylprednisolone, hydrocortisone, nor aldosterone result in a significant, acute effect upon CSF production. Similarly, CSF absorption and outflow resistance mechanisms are not acutely affected by intravenous methylprednisolone, hydrocortisone, and aldosterone. Dexamethasone also probably does not produce an immediate effect upon CSF absorption.