The effects of salicylates on rat and chicken liver acetyl-CoA carboxylase were investigated. Acetyl salicylate (2.5 mM) mimicked the activating effect of citrate on rat liver carboxylase if included during the preincubation period. The dissociated inactive form of chicken liver carboxylase could be reconstituted into the partially active form after dialysis against reconstitution buffer containing acetyl salicylate (2.5 mM) instead of citrate (20 mM). However, the inclusion of salicylates (acetyl- or sodium-) in the carboxylase assay medium resulted in inhibition (ranging from 24 to 32 per cent) of both the rat and chicken liver carboxylase activities. © 1979.