The Authors have studied corticosteron output and tissue levels of cAMP during superfusion with ACTH and/or PGE2 before and after preincubation with indometacin (2 microgram/ml) in beef adrenal glands isolated and superfused with Ringer solution. The Authors on the basis of Mieir studies, conclude that PGE2 can be considered as fixed intermediares of the corticosteroidogenetic action of ACTH.