The effects of prenatal morphine exposure (E11-18) on mineralocorticoid receptor (MR) modulation of synaptic plasticity were investigated in the lateral perforant path (LPP)-dentate gyrus granule cell synaptic system. canrenoic acid decreases the efficacy of the basal synaptic transmission in the LPP as well as suppresses synaptic plasticity in saline-exposed males. However, in adult morphine-exposed male rats canrenoic acid has no other or further effects than a saline treatment suggesting that prenatal morphine exposure suppresses MR-dependent basal synaptic transmission as well as synaptic plasticity.