We established a murine monoclonal antibody (MAb) specific for ganglioside GM4 by immunizing C3H/HeN mice with chemically synthesized GM4 adsorbed to Salmonella minnesota, followed by fusion with mouse myeloma cells. The MAb, designated as AMR10, was shown to exhibit high binding specificity, reacting only with the ganglioside GM4 used for immunization and native GM4 from human brain. We determined the distribution of GM4 in adult chicken cerebellum by means of the immunofluorescence technique with the MAb. Our study revealed that GM4 expression was associated with astrocytes in the granular layer and the white matter, but not with myelin in any layers of the chicken cerebellar cortex.