High-resolution detection of specific molecules in cells is a major challenge in biology. We show that infrared scanning near-field microscopy can detect the spatial distribution of α -amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid–type glutamate receptor clusters on hippocampal neurons. The GluR2 subunits were labeled with the die Alexa 488 and high-resolution infrared micrographs were taken at 6.25 μ m . The absence of photobleaching makes this approach suitable for a long-term observation and allows to localize different infrared-absorbing molecules over the complex background of other cell components.