The avian hippocampal formation (HF) is reported to have a role equivalent to that of the mammalian hippocampus, which may involve the glutamatergic system as well. In the present paper we offer evidence of the occurrence and distribution of the subunits composing AMPA-type glutamate receptors on neurons in the hippocampus region of the pigeon brain. The experiment analyzed the immunolabeling of glutamate receptor (GluR)1, GluR4, and GluR2/3 receptor subunits in adult pigeons and found consistent evidence that neurons located in the five main areas of the avian HF have these AMPA-type subunits, but their incidence varies according to position and neuro-type. About 20%-35% of the irregular and 35%-70% of the triangular neurons on the lateral and medial "V" arms contain GluR1 and GluR2/3, while GluR4 was found only at rounded neurons. 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