Monoclonal antibodies (Mab) RB13-2, JONES, and D1.1 all recognize gangliosides expressed on the surface of prenatal rat brain cells. As shown by high-performance thin-layer chromatography (HPTLC) immunoblotting of enriched rat brain gangliosides from different stages of development, all these Mabs bind to O-acetylated GD3 and (weakly) to an as yet unidentified double-band. Both Mab RB13-2 and Mab D1.1 recognize two additional minor gangliosides. Immunofluorescence analyses of frozen serial sections of prenatal rat brain show that, in addition to the cell subpopulations stained with all three antibodies, Mab RB13-2 and Mab D1.1 recognize further subpopulations of neural cells. These additional Mab JONES-negative cells apparently express minor ganglioside(s) identified in the immunoblots.