[³H]Glycine was observed to bind to channel catfish brain particles in a manner displaying saturation kinetics. The dissociation constant was calculated to be 7.38 ± 2.11 µM. Though some binding occurred in the absence of Na⁺ ions, the presence of such ions stimulated binding in a concentration-dependent manner. Similarly, chloride ions had a stimulatory effect on [³H]glycine binding. Several inhibitors of binding were identified, the most effective being β-alanine, pipecolic acid, 2,3-pyrazine dicarboxylic acid and 3,5-pyrazole dicarboxylic acid. Each is a structural analogue of glycine. Harmaline, a known inhibitor of Na⁺ binding, also inhibited glycine binding. A previous study had shown the presence of a sodium-dependent, active uptake system for glycine in synaptosomes derived from catfish brain. The present results suggest that the binding of [³H]glycine was to a glycine transporter and that the amino acid functions as a neurotransmitter in this species.